Try Hijackthis. Make sure you cross-check before deleting system files. You don't want to damage your system by deleting important files. But, Hijackthis is quite powerful to tell you what many anti-virus softwares can't tell.

So, download Hijackthis and run it. Save the log file, and analyze it in hijackthis.de. Then, if it shows some problems, then delete those files. If you cannot delete in the normal mode, go to safe mode and delete those files. Hope this helps...