diff --git a/src/TimerRecordDialog.cpp b/src/TimerRecordDialog.cpp
index ad5897eeb..e99b001e6 100644
--- a/src/TimerRecordDialog.cpp
+++ b/src/TimerRecordDialog.cpp
@@ -79,6 +79,11 @@ enum {
    POST_TIMER_RECORD_SHUTDOWN
 };
 
+// The slow timer interval is used to update the start and end times, which only show
+// time to the nearest second.  So we only need an update once a second.
+const int kSlowTimerInterval = 1000; // ms
+
+// This timer interval is used in some busy-wait loops and is much shorter.
 const int kTimerInterval = 50; // ms
 
 static double wxDateTime_to_AudacityTime(wxDateTime& dateTime)
@@ -177,7 +182,7 @@ TimerRecordDialog::TimerRecordDialog(wxWindow* parent, bool bAlreadySaved)
    m_pTimeTextCtrl_Duration->SetFieldFocus(3);
 
    m_timer.SetOwner(this, TIMER_ID);
-   m_timer.Start(kTimerInterval);
+   m_timer.Start(kSlowTimerInterval);
 
    // Do we need to tidy up when the timer recording has been completed?
    m_bProjectCleanupRequired = !(this->HaveFilesToRecover());
@@ -1019,7 +1024,15 @@ void TimerRecordDialog::UpdateEnd()
 {
    //v Use remaining disk -> record time calcs from AudacityProject::OnTimer to set range?
    m_DateTime_End = m_DateTime_Start + m_TimeSpan_Duration;
+   //wxLogDebug( "Time start %s end %s", 
+   //   m_DateTime_Start.FormatISOCombined(' '),
+   //   m_DateTime_End.FormatISOCombined(' ') );
+
+   // Disable the range limitation (to fix Bug 1749 and 1978)
+   // Otherwise SetVallue asserts when going back in time.
+   m_pDatePickerCtrl_End->SetRange(wxInvalidDateTime, wxInvalidDateTime); 
    m_pDatePickerCtrl_End->SetValue(m_DateTime_End);
+   // Re-enable range limitation to constrain user input.
    m_pDatePickerCtrl_End->SetRange(m_DateTime_Start, wxInvalidDateTime); // No backdating.
    m_pDatePickerCtrl_End->Refresh();
    m_pTimeTextCtrl_End->SetValue(wxDateTime_to_AudacityTime(m_DateTime_End));