diff --git a/Graphs/gFlagsLine.cpp b/Graphs/gFlagsLine.cpp
index 4827f310..886274e9 100644
--- a/Graphs/gFlagsLine.cpp
+++ b/Graphs/gFlagsLine.cpp
@@ -151,9 +151,13 @@ void gFlagsLine::paint(gGraph & w,int left, int top, int width, int height)
     int idx;
     QHash<ChannelID,QVector<EventList *> >::iterator cei;
 
+    qint64 clockdrift=qint64(PROFILE.cpap->clockDrift()) * 1000L;
+    qint64 drift=0;
+
     for (QVector<Session *>::iterator s=m_day->begin();s!=m_day->end(); s++) {
         if (!(*s)->enabled())
             continue;
+        drift=((*s)->machine()->GetType()==MT_CPAP) ? clockdrift : 0;
 
         cei=(*s)->eventlist.find(m_code);
         if (cei==(*s)->eventlist.end())
@@ -162,7 +166,7 @@ void gFlagsLine::paint(gGraph & w,int left, int top, int width, int height)
         QVector<EventList *> & evlist=cei.value();
         for (int k=0;k<evlist.size();k++) {
             EventList & el=*(evlist[k]);
-            start=el.first();
+            start=el.first() + drift;
             tptr=el.rawTime();
             dptr=el.rawData();
             int np=el.count();
diff --git a/Graphs/gLineChart.cpp b/Graphs/gLineChart.cpp
index 2d2fa36c..e5486fa0 100644
--- a/Graphs/gLineChart.cpp
+++ b/Graphs/gLineChart.cpp
@@ -174,6 +174,8 @@ void gLineChart::paint(gGraph & w,int left, int top, int width, int height)
     int total_points=0;
     int total_visible=0;
     bool square_plot,accel;
+    qint64 clockdrift=qint64(PROFILE.cpap->clockDrift()) * 1000L;
+    qint64 drift=0;
 
     QHash<ChannelID,QVector<EventList *> >::iterator ci;
 
@@ -195,6 +197,9 @@ void gLineChart::paint(gGraph & w,int left, int top, int width, int height)
                 qWarning() << "gLineChart::Plot() NULL Session Record.. This should not happen";
                 continue;
             }
+
+            drift=(sess->machine()->GetType()==MT_CPAP) ? clockdrift : 0;
+
             if (!sess->enabled()) continue;
             schema::Channel ch=schema::channel[code];
             bool fndbetter=false;
@@ -242,8 +247,8 @@ void gLineChart::paint(gGraph & w,int left, int top, int width, int height)
                 int siz=evec[n]->count();
                 if (siz<=1) continue; // Don't bother drawing 1 point or less.
 
-                x0=el.time(0);
-                xL=el.time(siz-1);
+                x0=el.time(0)+drift;
+                xL=el.time(siz-1)+drift;
 
                 if (maxx<x0) continue;
                 if (xL<minx) continue;
@@ -343,8 +348,8 @@ void gLineChart::paint(gGraph & w,int left, int top, int width, int height)
 //                } else lines->setSize(1);
 
                 if (el.type()==EVL_Waveform) {  // Waveform Plot
-                    if (idx>sam) idx-=sam;
-                    time=el.time(idx);
+                    if (idx > sam) idx-=sam;
+                    time=el.time(idx) + drift;
                     double rate=double(sr)*double(sam);
                     EventStoreType * ptr=el.rawData()+idx;
 
@@ -474,7 +479,7 @@ void gLineChart::paint(gGraph & w,int left, int top, int width, int height)
                     // Standard events/zoomed in Plot
                     //////////////////////////////////////////////////////////////////
 
-                    double start=el.first();
+                    double start=el.first() + drift;
 
                     quint32 * tptr=el.rawTime();
 
@@ -728,11 +733,14 @@ void AHIChart::SetDay(Day *d)
         EventDataType ahi=0;
         int cnt=0;
 
+        qint64 clockdrift=(qint64(PROFILE.cpap->clockDrift())*1000L),drift=0;
+
         bool fnd=false;
         for (s=d->begin();s!=d->end();s++) {
             if (!(*s)->enabled()) continue;
             Session *sess=*s;
-            if ((ti<sess->first()) || (f>sess->last())) continue;
+            if ((ti < sess->first()) || (f > sess->last())) continue;
+            drift=(sess->machine()->GetType()==MT_CPAP) ? clockdrift : 0;
 
             // Drop off suddenly outside of sessions
             //if (ti>sess->last()) continue;
@@ -764,7 +772,7 @@ void AHIChart::SetDay(Day *d)
             for (int i=0;i<znt;i++) {
                 if (!el[i]) continue;
                 for (quint32 j=0;j<el[i]->count();j++) {
-                    t=el[i]->time(j);
+                    t=el[i]->time(j)+drift;
                     if ((t>=f) && (t<ti)) {
                         cnt++;
                     }
diff --git a/Graphs/gLineOverlay.cpp b/Graphs/gLineOverlay.cpp
index 950023bd..daa36802 100644
--- a/Graphs/gLineOverlay.cpp
+++ b/Graphs/gLineOverlay.cpp
@@ -69,6 +69,10 @@ void gLineOverlayBar::paint(gGraph & w, int left, int topp, int width, int heigh
     OverlayDisplayType odt=PROFILE.appearance->overlayType();
     QHash<ChannelID,QVector<EventList *> >::iterator cei;
     int count;
+
+    qint64 clockdrift=qint64(PROFILE.cpap->clockDrift()) * 1000L;
+    qint64 drift=0;
+
     // For each session, process it's eventlist
     for (QVector<Session *>::iterator s=m_day->begin();s!=m_day->end(); s++) {
 
@@ -77,12 +81,13 @@ void gLineOverlayBar::paint(gGraph & w, int left, int topp, int width, int heigh
         if (cei==(*s)->eventlist.end()) continue;
         QVector<EventList *> & evlist=cei.value();
         if (evlist.size()==0) continue;
+        drift=((*s)->machine()->GetType()==MT_CPAP) ? clockdrift : 0;
 
         // Could loop through here, but nowhere uses more than one yet..
         for (int k=0;k<evlist.size();k++) {
             EventList & el=*(evlist[k]);
             count=el.count();
-            stime=el.first();
+            stime=el.first() + drift;
             dptr=el.rawData();
             eptr=dptr+count;
             tptr=el.rawTime();
diff --git a/Graphs/gSummaryChart.cpp b/Graphs/gSummaryChart.cpp
index 76a02f8f..4dc06707 100644
--- a/Graphs/gSummaryChart.cpp
+++ b/Graphs/gSummaryChart.cpp
@@ -107,6 +107,7 @@ void SummaryChart::SetDay(Day * nullday)
     }
     int suboffset;
     SummaryType type;
+
     for (QMap<QDate,QList<Day *> >::iterator d=PROFILE.daylist.begin();d!=PROFILE.daylist.end();d++) {
         tt=QDateTime(d.key(),QTime(0,0,0),Qt::UTC).toTime_t();
         dn=tt/86400;
diff --git a/SleepLib/calcs.cpp b/SleepLib/calcs.cpp
index ffa163fc..70fb0b92 100644
--- a/SleepLib/calcs.cpp
+++ b/SleepLib/calcs.cpp
@@ -4,6 +4,10 @@
  License: GPL
 */
 
+#include <QMutex>
+#include <QFile>
+#include <QDataStream>
+#include <QTextStream>
 #include <cmath>
 #include <algorithm>
 
@@ -908,7 +912,6 @@ int calcAHIGraph(Session *session)
         session->setAvg(CPAP_RDI,avgrdi);
     return cnt;
 }
-
 struct TimeValue {
     TimeValue() {
         time=0;
@@ -925,13 +928,11 @@ struct TimeValue {
     qint64 time;
     EventStoreType value;
 };
-bool operator<(const TimeValue &p1, const TimeValue & p2) {
-    return p1.time < p2.time;
-}
 
 struct zMaskProfile {
 public:
     zMaskProfile(MaskType type, QString name);
+    ~zMaskProfile();
 
     void reset() { pressureleaks.clear(); }
     void scanLeaks(Session * session);
@@ -939,28 +940,86 @@ public:
     void updatePressureMin();
     void updateProfile(Session * session);
 
+    void load(Profile * profile);
+    void save();
+
+    QMap<EventStoreType, EventDataType> pressuremax;
     QMap<EventStoreType, EventDataType> pressuremin;
+    QMap<EventStoreType, EventDataType> pressurecount;
+    QMap<EventStoreType, EventDataType> pressuretotal;
+    QMap<EventStoreType, EventDataType> pressuremean;
+    QMap<EventStoreType, EventDataType> pressurestddev;
 
     QVector<TimeValue> Pressure;
 
+    EventDataType calcLeak(EventStoreType pressure);
+
 protected:
+    static const quint32 version=0;
     void scanLeakList(EventList * leak);
     void scanPressureList(EventList * el);
 
     MaskType    m_type;
     QString     m_name;
+    Profile     * m_profile;
+    QString     m_filename;
 
-
-    // QHash<pressure, QMap<leak, leakcount> >
-    QHash<EventStoreType, QMap<EventStoreType,quint32> > pressureleaks;
-
-    //QHash<EventStoreType, int> pressurecount;
-
+    QMap<EventStoreType, QMap<EventStoreType,quint32> > pressureleaks;
+    EventDataType maxP,minP,maxL,minL,m_factor;
 };
+
+
+bool operator<(const TimeValue &p1, const TimeValue & p2) {
+    return p1.time < p2.time;
+}
+
 zMaskProfile::zMaskProfile(MaskType type, QString name)
     :m_type(type), m_name(name)
 {
 }
+zMaskProfile::~zMaskProfile()
+{
+    save();
+}
+
+void zMaskProfile::load(Profile * profile)
+{
+    m_profile=profile;
+    m_filename=m_profile->Get("{"+STR_GEN_DataFolder+"}/MaskProfile.mp");
+    QFile f(m_filename);
+    if (!f.open(QFile::ReadOnly))
+        return;
+
+    QDataStream in(&f);
+    in.setVersion(QDataStream::Qt_4_6);
+    in.setByteOrder(QDataStream::LittleEndian);
+
+    quint32 m,v;
+    in >> m;
+    in >> v;
+    if (m!=magic) {
+        qDebug() << "Magic wrong in zMaskProfile::load";
+    }
+
+    in >> pressureleaks;
+    f.close();
+}
+void zMaskProfile::save()
+{
+    QFile f(m_filename);
+    if (!f.open(QFile::WriteOnly))
+        return;
+
+    QDataStream out(&f);
+    out.setVersion(QDataStream::Qt_4_6);
+    out.setByteOrder(QDataStream::LittleEndian);
+
+    out << (quint32)magic;
+    out << (quint32)version;
+
+    out << pressureleaks;
+    f.close();
+}
 
 void zMaskProfile::scanPressureList(EventList * el)
 {
@@ -1026,30 +1085,37 @@ void zMaskProfile::scanLeakList(EventList * el)
 
         found=false;
         pressure=Pressure[0].value;
-        for (int i=0;i<Pressure.size()-1;i++) {
-            const TimeValue & p1=Pressure[i];
-            const TimeValue & p2=Pressure[i+1];
+        if (Pressure.size()>1) {
+            for (int i=0;i<Pressure.size()-1;i++) {
+                const TimeValue & p1=Pressure[i];
+                const TimeValue & p2=Pressure[i+1];
 
-            if ((p2.time > ti) && (p1.time <= ti)) {
-                pressure=p1.value;
-                found=true;
-                break;
-            } else if (p2.time==ti) {
-                pressure=p2.value;
-                found=true;
-                break;
+                if ((p2.time > ti) && (p1.time <= ti)) {
+                    pressure=p1.value;
+                    found=true;
+                    break;
+                } else if (p2.time==ti) {
+                    pressure=p2.value;
+                    found=true;
+                    break;
+                }
             }
+        } else {
+            found=true;
         }
         if (found) {
             pressureleaks[pressure][leak]++;
-            pmin=pressuremin.find(pressure);
-            fleak=EventDataType(leak) * gain;
-            if (pmin==pressuremin.end()) {
-                pressuremin[pressure]=fleak;
-            } else {
-                if (pmin.value() > fleak)
-                    pmin.value()=fleak;
-            }
+//            pmin=pressuremin.find(pressure);
+//            fleak=EventDataType(leak) * gain;
+//            if (pmin==pressuremin.end()) {
+//                pressuremin[pressure]=fleak;
+//                pressurecount[pressure]=pressureleaks[pressure][leak];
+//            } else {
+//                if (pmin.value() > fleak) {
+//                    pmin.value()=fleak;
+//                    pressurecount[pressure]=pressureleaks[pressure][leak];
+//                }
+//            }
         } else {
             int i=5;
         }
@@ -1066,7 +1132,7 @@ void zMaskProfile::scanLeaks(Session * session)
 }
 void zMaskProfile::updatePressureMin()
 {
-    QHash<EventStoreType, QMap<EventStoreType,quint32> >::iterator it;
+    QMap<EventStoreType, QMap<EventStoreType,quint32> >::iterator it;
 
     EventStoreType pressure;
     //EventDataType perc=0.1;
@@ -1074,7 +1140,7 @@ void zMaskProfile::updatePressureMin()
     //int idx1, idx2,
     int lks;
     double SN;
-    double percentile=0.75;
+    double percentile=0.40;
 
     double p=100.0*percentile;
     double nth,nthi;
@@ -1105,6 +1171,11 @@ void zMaskProfile::updatePressureMin()
         k=0;
 
         bool found=false;
+        double total=0;
+        for (QMap<EventStoreType,quint32>::iterator lit=leakmap.begin();lit!=leakmap.end();lit++,k++) {
+            total+=lit.value();
+        }
+        pressuretotal[pressure]=total;
         for (QMap<EventStoreType,quint32>::iterator lit=leakmap.begin();lit!=leakmap.end();lit++,k++) {
         //for (k=0;k < N;k++) {
             v1=lit.key();
@@ -1113,6 +1184,7 @@ void zMaskProfile::updatePressureMin()
 
             if (sum1 > nthi) {
                 pressuremin[pressure]=v1;
+                pressurecount[pressure]=w1;
                 found=true;
                 break;
             }
@@ -1123,6 +1195,7 @@ void zMaskProfile::updatePressureMin()
         if (found) continue;
         if (k>=N) {
             pressuremin[pressure]=v1;
+            pressurecount[pressure]=w1;
             continue;
         }
 
@@ -1140,30 +1213,19 @@ void zMaskProfile::updatePressureMin()
         // calculate linear interpolation
         double v=v1 + ((p-p1)/(p2-p1)) * (v2-v1);
         pressuremin[pressure]=v;
+        pressurecount[pressure]=w1;
 
     }
+}
 
+EventDataType zMaskProfile::calcLeak(EventStoreType pressure)
+{
+    if (maxP==minP)
+        return pressuremin[pressure];
 
-//    for (it=pressureleaks.begin();it!=pressureleaks.end();it++) {
-//        pressure=it.key();
-//        QMap<EventStoreType,quint32> & leakmap = it.value();
-//        lks=leakmap.size();
-//        tmp=perc * EventDataType(lks);
-//        idx1=floor(tmp);
-//        idx2=ceil(tmp);
-//        if (idx1==idx2) {
-//            pressuremin[pressure]=(leakmap.begin()+int(idx1)).key();
-//        } else if (idx1==lks-1) {
-//            pressuremin[pressure]=(leakmap.begin()+int(idx1)).key();
-//        } else {
-//            l1=(leakmap.begin()+int(idx1)).key();
-//            l2=(leakmap.begin()+int(idx2)).key();
-//            tmp=l1+(l2-l1)*(tmp-idx1);
-//            pressuremin[pressure]=tmp;
-//        }
+    EventDataType leak=(pressure-minP) * (m_factor) + minL;
+    return leak;
 
-//    }
-    //QMap<EventStoreType, EventDataType> pressuremin;
 }
 
 void zMaskProfile::updateProfile(Session * session)
@@ -1171,18 +1233,161 @@ void zMaskProfile::updateProfile(Session * session)
     scanPressure(session);
     scanLeaks(session);
     updatePressureMin();
+
+
+    if (pressuremin.size()<=1) {
+        maxP=minP=0;
+        maxL=minL=0;
+        m_factor=0;
+        return;
+    }
+    EventDataType p,l,tmp,mean,sum;
+    minP=250,maxP=0;
+    minL=1000, maxL=0;
+
+    long cnt=0, vcnt;
+    int n;
+
+    EventDataType maxcnt, maxval, lastval, lastcnt;
+
+    for (QMap<EventStoreType, QMap<EventStoreType,quint32> >::iterator it=pressureleaks.begin();it!=pressureleaks.end();it++)  {
+        p=it.key();
+        l=pressuremin[p];
+        QMap<EventStoreType,quint32> & leakval=it.value();
+        cnt=0;
+        vcnt=-1;
+        n=leakval.size();
+        sum=0;
+
+        maxcnt=0, maxval=0, lastval=0, lastcnt=0;
+        for (QMap<EventStoreType,quint32>::iterator lit=leakval.begin();lit!=leakval.end();lit++) {
+            cnt+=lit.value();
+            if (lit.value() > maxcnt) {
+                lastcnt=maxcnt;
+                maxcnt=lit.value();
+                lastval=maxval;
+                maxval=lit.key();
+
+            }
+            sum+=lit.key() * lit.value();
+            if (lit.key()==(EventStoreType)l) {
+                vcnt=lit.value();
+            }
+        }
+        pressuremean[p]=mean=sum / EventDataType(cnt);
+        if (lastval > 0) {
+            maxval=qMax(maxval,lastval); //((maxval*maxcnt)+(lastval*lastcnt)) / (maxcnt+lastcnt);
+        }
+        pressuremax[p]=lastval;
+        sum=0;
+        for (QMap<EventStoreType,quint32>::iterator lit=leakval.begin();lit!=leakval.end();lit++) {
+            tmp=lit.key()-mean;
+            sum+=tmp * tmp;
+        }
+        pressurestddev[p]=tmp=sqrt(sum / EventDataType(n));
+
+        if (vcnt>=0) {
+            tmp=1.0 / EventDataType(cnt) * EventDataType(vcnt);
+
+        }
+    }
+    QMap<EventStoreType, EventDataType> pressureval;
+    QMap<EventStoreType, EventDataType> pressureval2;
+    EventDataType max=0,tmp2,tmp3;
+    for (QMap<EventStoreType, EventDataType>::iterator it=pressuretotal.begin();it!=pressuretotal.end();it++) {
+        if (max < it.value()) max=it.value();
+    }
+    for (QMap<EventStoreType, EventDataType>::iterator it=pressuretotal.begin();it!=pressuretotal.end();it++) {
+        p=it.key();
+        tmp=pressurecount[p];
+        tmp2=it.value();
+
+        tmp3=(tmp / tmp2) * (tmp2 / max);
+        if (tmp3 > 0.05) {
+            tmp=pressuremean[p];
+            if (tmp>0) {
+                pressureval[p]=tmp; // / tmp2;
+                if (p < minP) minP = p;
+                if (p > maxP) maxP = p;
+                if (tmp < minL) minL = tmp;
+                if (tmp > maxL) maxL = tmp;
+            }
+        }
+    }
+
+    if ((maxP==minP)  || (minL==maxL) || (minP==250) || (minL==1000)) {
+        // crappy data set
+        maxP=minP=0;
+        maxL=minL=0;
+        m_factor=0;
+        return;
+    }
+    m_factor = (maxL - minL) / (maxP - minP);
+
+//    for (QMap<EventStoreType, EventDataType>::iterator it=pressuremin.begin();it!=pressuremin.end()-1;it++) {
+//        p1=it.key();
+//        p2=(it+1).key();
+//        l1=it.value();
+//        l2=(it+1).value();
+//        if (l2 > l1) {
+//            factor=(l2 - l1) / (p2 - p1);
+//            sum+=factor;
+//            cnt++;
+//        }
+//    }
+
+//    m_factor=sum/double(cnt);
+
+//    int i=0;
+//    if (i==1) {
+//        QFile f("/home/mark/leaks.csv");
+//        f.open(QFile::WriteOnly);
+//        QTextStream out(&f);
+//        EventDataType p,l,c;
+//        QString fmt;
+//        for (QMap<EventStoreType, EventDataType>::iterator it=pressuremin.begin();it!=pressuremin.end();it++) {
+//            p=EventDataType(it.key()/10.0);
+//            l=it.value();
+//            fmt=QString("%1,%2\n").arg(p,0,'f',1).arg(l);
+//            out << fmt;
+//        }
+
+    // cruft
+//        for (QMap<EventStoreType, QMap<EventStoreType,quint32> >::iterator it=pressureleaks.begin();it!=pressureleaks.end();it++)  {
+//            QMap<EventStoreType,quint32> & leakval=it.value();
+//            for (QMap<EventStoreType,quint32>::iterator lit=leakval.begin();lit!=leakval.end();lit++) {
+//                l=lit.key();
+//                c=lit.value();
+//                fmt=QString("%1,%2,%3\n").arg(p,0,'f',2).arg(l).arg(c);
+//                out << fmt;
+//            }
+//        }
+//        f.close();
+//    }
 }
 
-zMaskProfile maskProfile(Mask_NasalPillows,"ResMed Swift FX");
+QMutex zMaskmutex;
+zMaskProfile mmaskProfile(Mask_NasalPillows,"ResMed Swift FX");
+bool mmaskFirst=true;
 
 int calcLeaks(Session *session)
 {
+
     if (session->machine()->GetType()!=MT_CPAP) return 0;
     if (session->eventlist.contains(CPAP_Leak)) return 0; // abort if already there
     if (!session->eventlist.contains(CPAP_LeakTotal)) return 0; // can't calculate without this..
 
-   // maskProfile.reset();
-    maskProfile.updateProfile(session);
+    zMaskmutex.lock();
+    zMaskProfile * maskProfile=&mmaskProfile;
+    if (mmaskFirst) {
+        mmaskFirst=false;
+        maskProfile->load(p_profile);
+    }
+//    if (!maskProfile) {
+//        maskProfile=new zMaskProfile(Mask_NasalPillows,"ResMed Swift FX");
+//    }
+    maskProfile->reset();
+    maskProfile->updateProfile(session);
 
     EventList *leak=session->AddEventList(CPAP_Leak,EVL_Event,1);
 
@@ -1204,10 +1409,10 @@ int calcLeaks(Session *session)
             ti=start+ *tptr++;
 
             found=false;
-            pressure=maskProfile.Pressure[0].value;
-            for (int i=0;i<maskProfile.Pressure.size()-1;i++) {
-                const TimeValue & p1=maskProfile.Pressure[i];
-                const TimeValue & p2=maskProfile.Pressure[i+1];
+            pressure=maskProfile->Pressure[0].value;
+            for (int i=0;i<maskProfile->Pressure.size()-1;i++) {
+                const TimeValue & p1=maskProfile->Pressure[i];
+                const TimeValue & p2=maskProfile->Pressure[i+1];
 
                 if ((p2.time > ti) && (p1.time <= ti)) {
                     pressure=p1.value;
@@ -1220,7 +1425,7 @@ int calcLeaks(Session *session)
                 }
             }
             if (found) {
-                val=tmp-maskProfile.pressuremin[pressure];
+                val=tmp-maskProfile->calcLeak(pressure);
 
                 if (val < 0) {
                     val=0;
@@ -1228,193 +1433,10 @@ int calcLeaks(Session *session)
 
                 leak->AddEvent(ti,val);
             }
-
         }
     }
+    zMaskmutex.unlock();
     return leak->count();
-
-
-    //if (session->settings[CPAP_Mode].toInt()>=MODE_BIPAP) return 0; // Don't bother calculating when in APAP mode
-
-
-//    int prescnt=0;
-//    EventStoreType pressure;
-//    if (session->eventlist.contains(CPAP_Pressure)) {
-//        prescnt=session->count(CPAP_Pressure);
-//        Pressure.reserve(prescnt);
-//        for (int j=0;j<session->eventlist[CPAP_Pressure].size();j++) {
-//            QVector<EventList *> & el=session->eventlist[CPAP_Pressure];
-//            for (int e=0;e<el.size();e++) {
-//                EventList & ev=*(el[e]);
-//                for (int i=0;i<ev.count();i++) {
-//                    pressure=ev.raw(i);
-//                    Pressure.push_back(TimeValue(ev.time(i),pressure));
-//                    pressurecount[pressure]++;
-//                }
-//            }
-//        }
-//    } else if (session->eventlist.contains(CPAP_IPAP)) {
-//        prescnt=session->count(CPAP_IPAP);
-//        Pressure.reserve(prescnt);
-//        for (int j=0;j<session->eventlist[CPAP_IPAP].size();j++) {
-//            QVector<EventList *> & el=session->eventlist[CPAP_IPAP];
-//            for (int e=0;e<el.size();e++) {
-//                EventList & ev=*(el[e]);
-//                for (int i=0;i<ev.count();i++) {
-//                    pressure=ev.raw(i);
-//                    Pressure.push_back(TimeValue(ev.time(i),pressure));
-//                    pressurecount[pressure]++;
-//                }
-//            }
-//        }
-//    }
-//    qSort(Pressure);
-////    const qint64 winsize=3600000;
-
-//    //qint64 first=session->first(), last=session->last(), f;
-
-//
-
-//    qint64 start,ti;
-//    quint32 * tptr;
-//    EventStoreType * dptr;
-//    EventDataType gain,val,tmp;
-
-
-//    int pcnt=0;
-
-//    for (int i=0;i<session->eventlist[CPAP_LeakTotal].size();i++) {
-//        EventList & el=*session->eventlist[CPAP_LeakTotal][i];
-//        gain=el.gain();
-//        dptr=el.rawData();
-//        tptr=el.rawTime();
-//        start=el.first();
-//        pcnt=0;
-
-//        for (unsigned j=0;j<el.count();j++) {
-//            tmp=*dptr++ * gain;
-//            ti=start+ *tptr++;
-
-//            pressure=Pressure.at(Pressure.size()-1).value;
-//            for (pcnt=0;pcnt < Pressure.size()-1;pcnt++) {
-
-//                const TimeValue & p1=Pressure[pcnt];
-//                const TimeValue & p2=Pressure[pcnt+1];
-
-//                if ((p2.time > ti) && (p1.time < ti)) {
-//                    pressure=p1.value;
-//                    break;
-//                }
-//            }
-
-//            if (pcnt > 0) pcnt--;
-
-//            // leak and pressure intersection
-
-
-
-//            pressureleaks[pressure].push_back(tmp);
-//            // pressure current leak value is at..
-//        }
-//    }
-//    if (pressureleaks.size()>2) {
-//        int i=5;
-//    }
-//    int size=0,siz,idx;
-//    EventDataType perc=0.05;
-//    EventDataType f1,f2,fidx,diff;
-//    QMap<EventStoreType, EventDataType> presleakmin;
-//    QHash<EventStoreType, QVector<EventDataType> >::iterator it;
-//    for (it=pressureleaks.begin();it!=pressureleaks.end();it++) {
-//        pressure=it.key();
-//        QVector<EventDataType> & leaks=it.value();
-//        siz=leaks.size();
-//        // Only keep mask pressure value if there is enough samples to be reasonably accurate
-
-////       if ((pls<60) || (siz > 10)) {
-//            // Grab the 'perc' percentile of leak data
-//            fidx=float(siz) * perc;
-//            idx=fidx;
-//            diff=fidx-float(idx);
-//            nth_element(leaks.begin(),leaks.begin()+idx,leaks.end());
-//            f1=leaks.at(idx);
-//            if (idx < (siz-1)) {
-//                nth_element(leaks.begin(),leaks.begin()+idx+1,leaks.end());
-//                f2=leaks.at(idx+1);
-//                val=f1 + (f2-f1)*diff;
-//            } else val=f1;
-//            presleakmin[pressure]=val;
-//  //      }
-
-//        size+=siz;
-//    }
-
-//    QMap<EventStoreType, EventDataType>::iterator pit=presleakmin.begin(),npit;
-//    EventStoreType k;
-
-//    EventDataType p1,p2,v1,v2;
-//    bool skip;
-
-//    ////////////////////////////////////////////////////////////////////////
-//    // Generate the Mask Profile
-//    ////////////////////////////////////////////////////////////////////////
-//    if (pressureleaks.size()>presleakmin.size()) {
-//        for (it=pressureleaks.begin();it!=pressureleaks.end();it++) {
-//            pressure=it.key();
-
-//            skip=false;
-//            for (pit=presleakmin.begin();pit!=presleakmin.end();pit++) {
-//                k=pit.key();
-//                // if already in pressure table, skip this record.
-//                if (k==pressure) {
-//                    skip=true;
-//                    break;
-//                }
-//                if (k > pressure) break;
-//            }
-//            if (skip) continue;
-
-//            // rewind a step if not at the beginning already
-//            npit=pit;
-//            if (pit!=presleakmin.begin()) pit--;
-
-//            if (npit==presleakmin.end()) { // last entry..
-//                //can do better here by calculate the general trend
-//                presleakmin[pressure]=pit.value();
-//                break;
-//            }
-//            if (npit==pit) { // first entry missing (unusual)
-//                presleakmin[pressure]=pit.value();
-//                continue;
-//            }
-
-//            p1=pit.key();
-//            v1=pit.value();
-//            p2=npit.key();
-//            v2=npit.value();
-
-//            // Interpolate the pressure value in between the two valid data samples.
-//            val= v1+ ((pressure-p1)/(p2-p1) * (v2-v1));
-//            presleakmin[pressure]=val;
-//        }
-
-//    }
-
-//    // Secret Evil algorithm :)
-//    QList<EventDataType> values;
-//    values.reserve(presleakmin.size());
-//    for (npit=presleakmin.begin();npit!=presleakmin.end();npit++) {
-//        values.push_back(npit.value());
-//    }
-//    qSort(values);
-//    int i=0;
-//    for (npit=presleakmin.begin();npit!=presleakmin.end();npit++) {
-//        npit.value()=values.at(i++);
-//    }
-//    if (presleakmin.size()>2) {
-//        int i=5;
-//    }
-
 }
 
 
diff --git a/SleepLib/day.cpp b/SleepLib/day.cpp
index 3e9d64b8..fab3601a 100644
--- a/SleepLib/day.cpp
+++ b/SleepLib/day.cpp
@@ -40,14 +40,14 @@ void Day::AddSession(Session *s)
         qWarning("Day::AddSession called with NULL session object");
         return;
     }
-    if (d_firstsession) {
-        d_firstsession=false;
-        d_first=s->first();
-        d_last=s->last();
-    } else {
-        if (d_first > s->first()) d_first = s->first();
-        if (d_last < s->last()) d_last = s->last();
-    }
+//    if (d_firstsession) {
+//        d_firstsession=false;
+//        d_first=s->first();
+//        d_last=s->last();
+//    } else {
+//        if (d_first > s->first()) d_first = s->first();
+//        if (d_last < s->last()) d_last = s->last();
+//    }
     sessions.push_back(s);
 }
 
diff --git a/SleepLib/day.h b/SleepLib/day.h
index 99a69d47..afd3787e 100644
--- a/SleepLib/day.h
+++ b/SleepLib/day.h
@@ -92,11 +92,11 @@ public:
     //! \brief Returns the last session time of this day
     qint64 last();
 
-    //! \brief Sets the first session time of this day
-    void setFirst(qint64 val) { d_first=val; }
+    // //! \brief Sets the first session time of this day
+    // void setFirst(qint64 val) { d_first=val; }
 
-    //! \brief Sets the last session time of this day
-    void setLast(qint64 val) { d_last=val; }
+    // //! \brief Sets the last session time of this day
+    // void setLast(qint64 val) { d_last=val; }
 
     //! \brief Returns the last session time of this day for the supplied Channel code
     qint64 first(ChannelID code);
@@ -156,7 +156,7 @@ protected:
     //! \brief A Vector containing all sessions for this day
     QVector<Session *> sessions;
     QHash<ChannelID, QHash<EventDataType, EventDataType> > perc_cache;
-    qint64 d_first,d_last;
+    //qint64 d_first,d_last;
 private:
     bool d_firstsession;
 };
diff --git a/SleepLib/loader_plugins/prs1_loader.cpp b/SleepLib/loader_plugins/prs1_loader.cpp
index 43147da0..9aa0c672 100644
--- a/SleepLib/loader_plugins/prs1_loader.cpp
+++ b/SleepLib/loader_plugins/prs1_loader.cpp
@@ -1430,3 +1430,4 @@ void PRS1Loader::Register()
 
 
 
+
diff --git a/SleepLib/machine.cpp b/SleepLib/machine.cpp
index 6c7b48f6..1a3b23cd 100644
--- a/SleepLib/machine.cpp
+++ b/SleepLib/machine.cpp
@@ -109,6 +109,8 @@ QDate Machine::AddSession(Session *s,Profile *p)
 
     sessionlist[s->session()]=s; // To make sure it get's saved later even if it's not wanted.
 
+    int drift=PROFILE.cpap->clockDrift();
+
     QDateTime d2=QDateTime::fromTime_t(s->first()/1000);
 
     QDate date=d2.date();
diff --git a/SleepLib/machine_common.h b/SleepLib/machine_common.h
index 316e029d..e0ae8b04 100644
--- a/SleepLib/machine_common.h
+++ b/SleepLib/machine_common.h
@@ -28,7 +28,6 @@ class BoundsError {};
 class OldDBVersion {};
 
 const quint32 magic=0xC73216AB; // Magic number for Sleepyhead Data Files.. Don't touch!
-const quint32 compmagic=0xC73216AC; // Magic number for Compressed Sleepyhead Data Files.. Don't touch!
 
 //const int max_number_event_fields=10;
 // This should probably move somewhere else
diff --git a/SleepLib/profiles.cpp b/SleepLib/profiles.cpp
index a7e1097b..1984d717 100644
--- a/SleepLib/profiles.cpp
+++ b/SleepLib/profiles.cpp
@@ -399,8 +399,8 @@ void Profile::RemoveSession(Session * sess)
                     if (!first || first>sess.first()) first=sess.first();
                     if (!last || last<sess.last()) last=sess.last();
                 }
-                day->setFirst(first);
-                day->setLast(last);
+                // day->setFirst(first);
+                // day->setLast(last);
                 return;
             }
         }
diff --git a/SleepLib/profiles.h b/SleepLib/profiles.h
index 93690657..b24db266 100644
--- a/SleepLib/profiles.h
+++ b/SleepLib/profiles.h
@@ -206,6 +206,7 @@ const QString STR_CS_UserEventDuration="UserEventDuration";
 const QString STR_CS_UserEventDuplicates="UserEventDuplicates";
 const QString STR_CS_AHIWindow="AHIWindow";
 const QString STR_CS_AHIReset="AHIReset";
+const QString STR_CS_ClockDrift="ClockDrift";
 
 // ImportSettings Strings
 const QString STR_IS_DaySplitTime="DaySplitTime";
@@ -417,6 +418,7 @@ public:
         if (!m_profile->contains(STR_CS_UserEventFlagging)) (*m_profile)[STR_CS_UserEventFlagging]=false;
         if (!m_profile->contains(STR_CS_AHIWindow)) (*m_profile)[STR_CS_AHIWindow]=60.0;
         if (!m_profile->contains(STR_CS_AHIReset)) (*m_profile)[STR_CS_AHIReset]=false;
+        if (!m_profile->contains(STR_CS_ClockDrift)) (*m_profile)[STR_CS_ClockDrift]=(int)0;
     }
 
     ~CPAPSettings() {}
@@ -442,6 +444,7 @@ public:
     double AHIWindow() { return (*m_profile)[STR_CS_AHIWindow].toDouble(); }
     bool AHIReset() { return (*m_profile)[STR_CS_AHIReset].toBool(); }
     bool userEventFlagging() { return (*m_profile)[STR_CS_UserEventFlagging].toBool(); }
+    int clockDrift() { return (*m_profile)[STR_CS_ClockDrift].toInt(); }
 
     //Setters
     void setMode(CPAPMode mode) { (*m_profile)[STR_CS_PrescribedMode]=(int)mode; }
@@ -462,6 +465,7 @@ public:
     void setAHIReset(bool reset) { (*m_profile)[STR_CS_AHIReset]=reset; }
     void setUserEventFlagging(bool flagging) { (*m_profile)[STR_CS_UserEventFlagging]=flagging; }
     void setUserEventDuplicates(bool dup) { (*m_profile)[STR_CS_UserEventDuplicates]=dup; }
+    void setClockDrift(int seconds) { (*m_profile)[STR_CS_ClockDrift]=(int)seconds; }
 
     Profile *m_profile;
 };
diff --git a/SleepLib/session.cpp b/SleepLib/session.cpp
index d60e6618..7f49fc5f 100644
--- a/SleepLib/session.cpp
+++ b/SleepLib/session.cpp
@@ -896,9 +896,15 @@ EventDataType Session::Max(ChannelID id)
 }
 qint64 Session::first(ChannelID id)
 {
+    qint64 drift=qint64(PROFILE.cpap->clockDrift())*1000L;
+    qint64 tmp;
     QHash<ChannelID,quint64>::iterator i=m_firstchan.find(id);
-    if (i!=m_firstchan.end())
-        return i.value();
+    if (i!=m_firstchan.end()) {
+        tmp=i.value();
+        if (s_machine->GetType()==MT_CPAP)
+            tmp+=drift;
+        return tmp;
+    }
 
     QHash<ChannelID,QVector<EventList *> >::iterator j=eventlist.find(id);
     if (j==eventlist.end())
@@ -917,14 +923,21 @@ qint64 Session::first(ChannelID id)
         }
     }
     m_firstchan[id]=min;
+    if (s_machine->GetType()==MT_CPAP)
+        min+=drift;
     return min;
 }
 qint64 Session::last(ChannelID id)
 {
+    qint64 drift=qint64(PROFILE.cpap->clockDrift())*1000L;
+    qint64 tmp;
     QHash<ChannelID,quint64>::iterator i=m_lastchan.find(id);
-    if (i!=m_lastchan.end())
-        return i.value();
-
+    if (i!=m_lastchan.end()) {
+        tmp=i.value();
+        if (s_machine->GetType()==MT_CPAP)
+            tmp+=drift;
+        return tmp;
+    }
     QHash<ChannelID,QVector<EventList *> >::iterator j=eventlist.find(id);
     if (j==eventlist.end())
         return 0;
@@ -943,6 +956,8 @@ qint64 Session::last(ChannelID id)
     }
 
     m_lastchan[id]=max;
+    if (s_machine->GetType()==MT_CPAP)
+        max+=drift;
     return max;
 }
 bool Session::channelDataExists(ChannelID id)
@@ -1427,3 +1442,17 @@ void Session::offsetSession(qint64 offset)
     qDebug() << "Session now starts" << QDateTime::fromTime_t(s_first/1000).toString("yyyy-MM-dd HH:mm:ss");
 
 }
+
+qint64 Session::first() {
+    qint64 start=s_first;
+    if (s_machine->GetType()==MT_CPAP)
+        start+=qint64(PROFILE.cpap->clockDrift())*1000L;
+    return start;
+}
+
+qint64 Session::last() {
+    qint64 last=s_last;
+    if (s_machine->GetType()==MT_CPAP)
+        last+=qint64(PROFILE.cpap->clockDrift())*1000L;
+    return last;
+}
diff --git a/SleepLib/session.h b/SleepLib/session.h
index d3ef5ccc..effa0507 100644
--- a/SleepLib/session.h
+++ b/SleepLib/session.h
@@ -71,14 +71,10 @@ public:
     void setEnabled(bool b);
 
     //! \brief Return the start of this sessions time range (in milliseconds since epoch)
-    qint64 first() {
-        return s_first;
-    }
+    qint64 first();
 
     //! \brief Return the end of this sessions time range (in milliseconds since epoch)
-    qint64 last() {
-        return s_last;
-    }
+    qint64 last();
 
     //! \brief Return the millisecond length of this session
     qint64 length() {
diff --git a/daily.cpp b/daily.cpp
index ecaff917..508eb570 100644
--- a/daily.cpp
+++ b/daily.cpp
@@ -460,6 +460,8 @@ void Daily::UpdateEventsTree(QTreeWidget *tree,Day *day)
     QHash<ChannelID,int> mccnt;
     int total_events=0;
     bool userflags=p_profile->cpap->userEventFlagging();
+
+    qint64 drift=0, clockdrift=PROFILE.cpap->clockDrift()*1000L;
     for (QVector<Session *>::iterator s=day->begin();s!=day->end();s++) {
         if (!(*s)->enabled()) continue;
 
@@ -486,6 +488,7 @@ void Daily::UpdateEventsTree(QTreeWidget *tree,Day *day)
                 && (code!=CPAP_VSnore)) continue;
 
             if (!userflags && ((code==CPAP_UserFlag1) || (code==CPAP_UserFlag2) || (code==CPAP_UserFlag3))) continue;
+            drift=(*s)->machine()->GetType()==MT_CPAP ? clockdrift : 0;
 
             QTreeWidgetItem *mcr;
             if (mcroot.find(code)==mcroot.end()) {
@@ -512,13 +515,13 @@ void Daily::UpdateEventsTree(QTreeWidget *tree,Day *day)
                 EventList & ev=*(m.value()[z]);
 
                 for (quint32 o=0;o<ev.count();o++) {
-                    qint64 t=ev.time(o);
+                    qint64 t=ev.time(o)+drift;
 
                     if (code==CPAP_CSR) { // center it in the middle of span
                         t-=float(ev.raw(o)/2.0)*1000.0;
                     }
                     QStringList a;
-                    QDateTime d=QDateTime::fromTime_t(t/1000);
+                    QDateTime d=QDateTime::fromTime_t(t/1000L);
                     QString s=QString("#%1: %2 (%3)").arg((int)(++mccnt[code]),(int)3,(int)10,QChar('0')).arg(d.toString("HH:mm:ss")).arg(m.value()[z]->raw(o));
                     a.append(s);
                     QTreeWidgetItem *item=new QTreeWidgetItem(a);
@@ -1302,10 +1305,15 @@ void Daily::Load(QDate date)
 
             ui->bookmarkTable->blockSignals(true);
 
+
+            qint64 clockdrift=PROFILE.cpap->clockDrift()*1000L,drift;
+            Day * dday=PROFILE.GetDay(previous_date,MT_CPAP);
+            drift=(dday!=NULL) ? clockdrift : 0;
+
             bool ok;
             for (int i=0;i<start.size();i++) {
-                qint64 st=start.at(i).toLongLong(&ok);
-                qint64 et=end.at(i).toLongLong(&ok);
+                qint64 st=start.at(i).toLongLong(&ok)+drift;
+                qint64 et=end.at(i).toLongLong(&ok)+drift;
 
                 QDateTime d=QDateTime::fromTime_t(st/1000L);
                 //int row=ui->bookmarkTable->rowCount();
@@ -1666,6 +1674,10 @@ void Daily::on_bookmarkTable_itemClicked(QTableWidgetItem *item)
     int row=item->row();
     qint64 st,et;
 
+//    qint64 clockdrift=PROFILE.cpap->clockDrift()*1000L,drift;
+//    Day * dday=PROFILE.GetDay(previous_date,MT_CPAP);
+//    drift=(dday!=NULL) ? clockdrift : 0;
+
     QTableWidgetItem *it=ui->bookmarkTable->item(row,1);
     bool ok;
     st=it->data(Qt::UserRole).toLongLong(&ok);
@@ -1712,8 +1724,15 @@ void Daily::on_addBookmarkButton_clicked()
     dw->setFlags(Qt::ItemIsSelectable|Qt::ItemIsEnabled);
     ui->bookmarkTable->setItem(row,0,dw);
     ui->bookmarkTable->setItem(row,1,tw);
-    tw->setData(Qt::UserRole,st);
-    tw->setData(Qt::UserRole+1,et);
+    qint64 clockdrift=PROFILE.cpap->clockDrift()*1000L,drift;
+    Day * day=PROFILE.GetDay(previous_date,MT_CPAP);
+    drift=(day!=NULL) ? clockdrift : 0;
+
+    // Counter CPAP clock drift for storage, in case user changes it later on
+    // This won't fix the text string names..
+
+    tw->setData(Qt::UserRole,st-drift);
+    tw->setData(Qt::UserRole+1,et-drift);
 
     ui->bookmarkTable->blockSignals(false);
     update_Bookmarks();
diff --git a/mainwindow.cpp b/mainwindow.cpp
index c6d825dc..e745b2fd 100644
--- a/mainwindow.cpp
+++ b/mainwindow.cpp
@@ -359,8 +359,9 @@ void MainWindow::on_action_Import_Data_triggered()
     }
     if (successful) {
         PROFILE.Save();
-        if (daily) daily->ReloadGraphs();
         if (overview) overview->ReloadGraphs();
+        on_summaryButton_clicked();
+        if (daily) daily->LoadDate(daily->getDate());
         if ((goodlocations.size()>0) && (QMessageBox::question(this,"Remember this Location?","Would you like to remember this import location for next time?\n"+newdir,QMessageBox::Yes,QMessageBox::No)==QMessageBox::Yes)) {
             for (int i=0;i<goodlocations.size();i++) {
                 importLocations.push_back(goodlocations[i]);
@@ -375,7 +376,6 @@ void MainWindow::on_action_Import_Data_triggered()
             }
             file.close();
         }
-        on_summaryButton_clicked();
     } else {
         mainwin->Notify("Import Problem\n\nCouldn't find any new Machine Data at the locations given");
     }
diff --git a/oximetry.cpp b/oximetry.cpp
index 0c897dcd..38cb6b7c 100644
--- a/oximetry.cpp
+++ b/oximetry.cpp
@@ -457,7 +457,7 @@ void CMS50Serial::import_process()
     while (i<(size-3)) {
         a=data.at(i++); // low bits are supposedly the high bits of the heart rate
         pl=((data.at(i++) & 0x7f) | ((a & 1) << 7)) & 0xff;
-        o2=data.at(i++);
+        o2=data.at(i++) & 0x7f;
         if (pl!=0) {
             if (lastpl!=pl) {
                 if (lastpl==0 || !pulse) {
@@ -709,7 +709,7 @@ void CMS50Serial::ReadyRead()
                 i+=3;
             } else {
                 pl=(bytes[i] & 0x7f) | hb;
-                o2=bytes[i+1];
+                o2=bytes[i+1] & 0x7f;
                 addPulse(lasttime,pl);
                 addSpO2(lasttime,o2);
                 i+=2;
@@ -1056,7 +1056,7 @@ void Oximetry::on_RunButton_toggled(bool checked)
         secondSPO2Update=true;
 
         qint64 f=oximeter->getSession()->first();
-        day->setFirst(f);
+        //day->setFirst(f);
         plethy->setMinX(f);
         pulse->setMinX(f);
         spo2->setMinX(f);
@@ -1091,7 +1091,7 @@ void Oximetry::data_changed()
 
     qint64 last=oximeter->lastTime();
     qint64 first=last-30000L;
-    day->setLast(last);
+    //day->setLast(last);
 
     plethy->setMinX(first);
     plethy->setMaxX(last);
@@ -1324,8 +1324,7 @@ void Oximetry::on_saveButton_clicked()
         oximeter->getMachine()->Save();
         day->getSessions().clear();
 
-
-        mainwin->getDaily()->ReloadGraphs();
+        mainwin->getDaily()->LoadDate(mainwin->getDaily()->getDate());
         mainwin->getOverview()->ReloadGraphs();
         GraphView->setEmptyText("No Oximetry Data");
         GraphView->redraw();
@@ -1398,7 +1397,7 @@ bool Oximetry::openSPOFile(QString filename)
     qint64 t2=session->first(OXI_SPO2);
     qint64 t3=qMin(t1,t2);
     session->set_first(t3);
-    day->setFirst(t3);
+    //day->setFirst(t3);
     int zi=t3/1000L;
     session->SetSessionID(zi);
     date.fromTime_t(zi);
@@ -1410,7 +1409,7 @@ bool Oximetry::openSPOFile(QString filename)
     t2=session->last(OXI_SPO2);
     t3=qMax(t1,t2);
     session->set_last(t3);
-    day->setLast(t3);
+    //day->setLast(t3);
     CONTROL->setVisible(false);
 
     updateGraphs();
@@ -1471,7 +1470,7 @@ bool Oximetry::openSPORFile(QString filename)
     qint64 t2=session->first(OXI_SPO2);
     qint64 t3=qMin(t1,t2);
     session->set_first(t3);
-    day->setFirst(t3);
+    //day->setFirst(t3);
     int zi=t3/1000L;
     session->SetSessionID(zi);
     date.fromTime_t(zi);
@@ -1484,7 +1483,7 @@ bool Oximetry::openSPORFile(QString filename)
     t2=session->last(OXI_SPO2);
     t3=qMax(t1,t2);
     session->set_last(t3);
-    day->setLast(t3);
+    //day->setLast(t3);
 
 
     //PLETHY->setVisible(false);
@@ -1599,8 +1598,8 @@ void Oximetry::updateGraphs()
     SPO2->setRecMinY(90);
     SPO2->setRecMaxY(100);
 
-    day->setFirst(first);
-    day->setLast(last);
+    //day->setFirst(first);
+    //day->setLast(last);
     pulse->setMinY(session->Min(OXI_Pulse));
     pulse->setMaxY(session->Max(OXI_Pulse));
     spo2->setMinY(session->Min(OXI_SPO2));
diff --git a/preferencesdialog.cpp b/preferencesdialog.cpp
index 31dfc574..d5faf328 100644
--- a/preferencesdialog.cpp
+++ b/preferencesdialog.cpp
@@ -161,6 +161,8 @@ PreferencesDialog::PreferencesDialog(QWidget *parent,Profile * _profile) :
     ui->skipLoginScreen->setChecked(PREF[STR_GEN_SkipLogin].toBool());
     ui->allowEarlyUpdates->setChecked(PREF[STR_PREF_AllowEarlyUpdates].toBool());
 
+    ui->clockDrift->setValue(profile->cpap->clockDrift());
+
     ui->skipEmptyDays->setChecked(profile->general->skipEmptyDays());
     ui->enableMultithreading->setChecked(profile->session->multithreading());
     ui->cacheSessionData->setChecked(profile->session->cacheSessions());
@@ -368,6 +370,8 @@ bool PreferencesDialog::Save()
     profile->session->setIgnoreShortSessions(ui->IgnoreSlider->value());
     profile->session->setDaySplitTime(ui->timeEdit->time());
 
+    profile->cpap->setClockDrift(ui->clockDrift->value());
+
     profile->appearance->setOverlayType((OverlayDisplayType)ui->overlayFlagsCombo->currentIndex());
     profile->cpap->setLeakMode(ui->leakModeCombo->currentIndex());
     profile->cpap->setMaskType((MaskType)ui->maskTypeCombo->currentIndex());
@@ -483,10 +487,10 @@ bool PreferencesDialog::Save()
     if (recalc_events) {
         // send a signal instead?
         mainwin->reprocessEvents(needs_restart);
+    } else if (needs_restart) {
+        mainwin->RestartApplication();
     } else {
-        if (needs_restart) {
-            mainwin->RestartApplication();
-        }
+        mainwin->getDaily()->LoadDate(mainwin->getDaily()->getDate());
     }
     return true;
 }
diff --git a/preferencesdialog.ui b/preferencesdialog.ui
index 867d6c5b..1401c588 100644
--- a/preferencesdialog.ui
+++ b/preferencesdialog.ui
@@ -10,7 +10,7 @@
     <x>0</x>
     <y>0</y>
     <width>640</width>
-    <height>421</height>
+    <height>429</height>
    </rect>
   </property>
   <property name="maximumSize">
@@ -42,7 +42,7 @@
    <item>
     <widget class="QTabWidget" name="tabWidget">
      <property name="currentIndex">
-      <number>5</number>
+      <number>1</number>
      </property>
      <widget class="QWidget" name="importTab">
       <attribute name="title">
@@ -609,7 +609,7 @@ p, li { white-space: pre-wrap; }
        </item>
        <item>
         <layout class="QGridLayout" name="gridLayout_11">
-         <item row="1" column="0" colspan="3">
+         <item row="1" column="0" colspan="2">
           <widget class="QCheckBox" name="AddRERAtoAHI">
            <property name="font">
             <font>
@@ -625,7 +625,7 @@ p, li { white-space: pre-wrap; }
            </property>
           </widget>
          </item>
-         <item row="2" column="0" colspan="3">
+         <item row="2" column="0" colspan="2">
           <widget class="QGroupBox" name="complianceGroupbox">
            <property name="toolTip">
             <string>Don't show any compliance information</string>
@@ -691,7 +691,7 @@ p, li { white-space: pre-wrap; }
            </layout>
           </widget>
          </item>
-         <item row="3" column="0" colspan="3">
+         <item row="3" column="0" colspan="2">
           <widget class="QGroupBox" name="customEventGroupbox">
            <property name="toolTip">
             <string>Enable/disable experimental event flagging enhancements. 
@@ -827,7 +827,7 @@ p, li { white-space: pre-wrap; }
            </layout>
           </widget>
          </item>
-         <item row="4" column="0" colspan="3">
+         <item row="4" column="0" colspan="2">
           <widget class="QGroupBox" name="ahiGraphGroupbox">
            <property name="title">
             <string>AHI/Hour Graph Settings</string>
@@ -904,6 +904,39 @@ Defaults to 60 minutes.. Highly recommend it's left at this value.</string>
            </property>
           </spacer>
          </item>
+         <item row="0" column="0">
+          <widget class="QLabel" name="label_44">
+           <property name="font">
+            <font>
+             <weight>75</weight>
+             <bold>true</bold>
+            </font>
+           </property>
+           <property name="text">
+            <string>CPAP Clock Drift</string>
+           </property>
+          </widget>
+         </item>
+         <item row="0" column="1">
+          <widget class="QSpinBox" name="clockDrift">
+           <property name="toolTip">
+            <string>Don't touch this unless you know your CPAP clock is out.
+Try to sync it to your PC's clock (which should be synced to a timeserver)</string>
+           </property>
+           <property name="suffix">
+            <string> seconds</string>
+           </property>
+           <property name="minimum">
+            <number>-7200</number>
+           </property>
+           <property name="maximum">
+            <number>7200</number>
+           </property>
+           <property name="value">
+            <number>0</number>
+           </property>
+          </widget>
+         </item>
         </layout>
        </item>
       </layout>