in Safe Mode? If so you can run your AV scanner from there.
What did you download?
When I turn on my PC it all seems fine until i finally log in. All that is there is my desktop background.. nothing else. And nothing else ever comes up.. and whenever I try to open task manager the computer freezes and I have to turn it off.
I think this may be due to a virus as I downloaded something and opened it without first virus checking it.
My PC is Dell Precision 350 with Windows XP.