Hey George,
I'd suggest you come hang around on the #pitivi IRC channel, try to poke the devs (bilboed, twi_, emdash) and see if they can help you get started on debugging the issue.

The mailing list is a bit too slow for complex debugging and is not used much.

Don't panic if you don't get an instantaneous answer on IRC, stick around, we may just be away from the computer or busy debugging something else (I often see people asking a question and leaving a few mins before I or someone else comes back to answer).