Corrupt MPEG Codec

I think I have some corrupt video codecs. Whenever I open a video file, the audio will play but the video will not. When I close out of the program, it makes my system freeze and I have to hit reset. Is this a video card problem? Or is it just a problem with to codecs installed? It started happening after I updated the video card driver and installed a new codec pack. If it is a problem with the codecs, how would you reinstall the original ones without reinstalling windows?

System Information:
Windows XP Professtional Service Pack 2
All Updates installed
ATI Radeon 7000 series 64MB video card
256MB RAM
Pentium 4 - 2.0GHz

Never mind, I got it fixed...It was a driver issue. !

THANK YOU