Rob:

Sorry you haven't gotten much response on your problem. I suspect that it's "specific" and possibly no one else is running the TCH interface.
Have you tried just running BIAB with one of the default MIDI and/or Synthesizer outputs (under Options > MIDI/Audio driver setup)?

Also, is it possible that it's the specific song file you're working on?
Perhaps try one of the sample files in the C:\bb folder and see if you get the same issue.

You could also try the excellent PGMusic Live Help and see if they can point you in the right direction.

Wish I could be more help.
Good luck!
LLOYD S