Help, computer infected, unknown virus!

Hello.
For last two days I am experiencing serious problems with my computer. Everything started when I was downloading something from rapidshare, and when file was downloaded, I saved it on my E partition, where I have my music and movies stored. At the beginning, everything was ok, but than after a day, I was going to watch one of the movies, when after few minutes I’ve noticed that the picture was getting strange and disordered by every next scene. My Crystal player notified me that he needs to close due to some errors. Next thing I know, I was getting the same messages from various applications such as ICQ, MSN, Winamp. I restarted my computer and than this messages was constantly showing up:

The system has recovered from a serious error…

Generic Host Process for Win32 Services has encountered a problem and needs to close...

and in my opinion, the problematic one,

wuauclt has encountered a problem and needs to close…

After that, I deleted a movie, which is likely to cause all this, and decided to formate C: partition. I was very unpleasantly surprised when I received same notifications after formatting and reinstalling my Windows. The problem remains and now I really have no clue what to do next.