Assuming you dont have anti-malware,
Spybot, ad-aware, a squared (but maybe not in that order). All downloaded from advise from this site. All used by myself. All work.
once you have these, run each in turn. follow their own help files/advice, but generally delete anty nasties they find. a squared is very slow, but give it time.
Then if you still have problems, post back.
If you do, over to others, perhaps too many running processes?