Interesting.

Experiments show it's related to tempo. For speeds below 119 the metronome window works fine, for speeds above it's always one beat late. For 119 the beat display is unstable.

Same for files with Realtracks or just midi, frozen or not.

System is Dell Laptop 1.7GHz, 1G RAM
XP Media Center Edition Version 2002 SP2 (and yes, this OS variant has been reported as problematic for BIAB).

John