Ok, that said, you can use Hijackthis on your PC (and of course a virus scanner). If it detects something, delete it. You should also check your Registry Keys, if there are any things overwritten by that hypothetical program. Just search for the program "regedit" on your computer to do that. I once had a virus, called "Conduit" which you can't remove from your computer in common ways. But doing these killed it (hopefully).