Can't Remove Video Codecs W2K

[ln108]

I've been trying to remove a number of video codecs (DivX 4, Xvid, etc.) from my W2K system. I've tried the Device Manager, Sound Video and Game Controller, Video Codec route, and also the Control Panel, Sounds and Multimedia route. I remove them, but they reappear when I reboot. I've tried going into Safe Mode, as the MS knowledge base suggests, but that doesn't help.

Can I edit the registry? Which files to remove?

Thanks,