Vista - Can't play Videos. At all.

I'm using Windows Vista Home Premium and have been for about three months
now, and its mostly been running fine (at least where this is concerned).
However, the other day I chucked an audio CD in the drive in order to listen
to some music and now everything has screwed up.

I tried to autorun the CD in WMP, and WMP refused to even start up. I ended
up installing Winamp instead which worked fine. The next day I discovered
that Vista won't now play any video files at all. WMP still refuses to start,
I also have Zoomplayer and Media Player Classic, and now Winamp, and none of
them will play videos anymore, bring up error messages about missing codecs
and filters. I already have a ton of codecs installed, divx, haali media
splitter, FFDshow etctc. I tried reinstalling all these, and the media
players, still won't work, I tried a system restore, and that didn't fix the
problem either.

I've been trying to fix this forever and am totally at my wits end with
this, can anyone help?