diff --git a/src/MixerBoard.cpp b/src/MixerBoard.cpp
index 407980150..deb89ca7f 100644
--- a/src/MixerBoard.cpp
+++ b/src/MixerBoard.cpp
@@ -419,6 +419,10 @@ void MixerTrackCluster::UpdateMeter(const double t0, const double t1)
    if ((t0 < 0.0) || (t1 < 0.0) || (t0 >= t1) || // bad time value or nothing to show
          ((mMixerBoard->HasSolo() || mLeftTrack->GetMute()) && !mLeftTrack->GetSolo()))
    {
+      // Vaughan, 2011-02-04: Now that we're updating all meters from audacityAudioCallback, 
+      //    this causes an assert if you click Mute while playing, because ResetMeter() resets 
+      //    the timer, and wxTimerbase says that can only be done from main thread -- 
+      //    but it seems to work fine.
       this->ResetMeter(false);
       return;
    }