True Piano soft synth stopped playing.

I've got a project that has a handful of True Piano tracks recorded and they sound great.  I recorded an additional True Piano track and suddenly all of the other True Piano tracks stopped playing.  The newly recorded track plays fine.  There are no mutes, solos or anything else that I can see, including track lanes, that would prevent the tracks from playing.  One other piece of info, the tracks that don't play display the midi info in white...they were previously in different colors depending on the track.  In fact, one of the tracks that doesn't play has the midi info displayed in white EXCEPT for the very last part of the track and that part still plays correctly.
 
Any ideas? 

Jim Roseberry
Perhaps a corrupt project file...
What happens if you past the tracks into a new/fresh project?

I  haven't tried that yet, however, I've re-recorded some of the problem tracks, over top of the originals, and they play without incident.  I may just re-record the remaining piano parts and call it a day.  Still, it would be nice to know what the heck is going on for future reference.

Are you running 64-bit Sonar?