Vocal Issues

I just came back to Sonar after a few month sebatical.  I opened the last project I worked on to see where I left off.  Strange issue happening on my three vocal tracks.  I play the file and the entire first verse is silent on all three vocal tracks.  Somewhere about track 30, all three vocal tracks can be heard.  The wave forms are shown in the track view and the lights bounce along with the vocals on the mixer, even though you can't hear it through the speakers.  These silent clips are properly associated with the wave files and they are 'on' or 'unmuted'.  The sliders on the mixer are up, even on the silent portion.  Any thoughts why these first 20-30 bars are silent, then the rest of the song works perfectly?
 
Thanks for all of your thoughts!
Patrick