I think this has been asked before but I got a virus or something that makes my background on the main page say :
Warning!
Spyware Detected on your Computer!
Install an antivirus or spyware remover
to clean your computer.
My dad's computer had that screen a few weeks ago. What i did was ran system restore and restored to a previous date. Then I ran avg virus scan, adaware, and Spybot search and destroy. I deleted all the crap it found, and now the computer is back to normal.
theres been alot of that spyware smitfraud recently,you should all have real time protection with anti spyware program to avoid this crap.
send in a HJT log to see whitch one it is, your probaly going to have to download smitrem and run that, spertti is the one to ask for this one.