This only started happening when I upgraded from a 2 or 3 month old version to 2.34.980.

CPU 1.8ghz 533mhz fsb mobile c2d
intel x3100 gpu
fully updated Vista 32bit
4GB DRR2

It occures when the window is resizes, and sometimes when it's maximized. Audio playback continues, but video play back freezes to the last rendered frame. I'm resizing via mouse wheel.