Riddle me this:
Fresh install of Windows XP, first thing I did was install SP1 and all security updates. Installed WinDVD. From both Media Player and WinDVD, playback on any DVD locks the application (not system) right the fuck up as soon as it tries to switch titles. My terminology may be bad here, but in Media Player it reports titles with chapters hanging under them. But I know for a fact that the failure is when title changes happen.
Extensive Googling and mskbasing give me no answers, but have helped narrow the problem down somewhat.
I think the problem stems from a combination of XP Service Pack 1 and the video card, a GeForce FX 5200 (eVGA). I've tried different video card drivers, from the eVGA approved one to the one available at nvidia.com. Unfortunately I did not test DVD playback before installing SP1, as I didn't expect the problem.

Absolutely no applications running on startup, so there's no interference there. The DVDROM (Samsung SD-616F) is on the latest firmware rev.
Any ideas?