Well, just now my computer told me that the administrator has disabled task manager, so now I know something's dreadfully wrong.
Seems like every 20 seconds a new instance of firefox opens up with some adware warning me about viruses, urging me to download their shit (onlinescannerxp.com is the malicious site in question, if anyone recognizes it). It changes my background to a flashing gif warning me about viruses, will constantly open up my documents for no reason, and there is a big red circle with a white x in the bottom right taskbar, that's never been there before.
As I said in the thread title, not MalwareBytes nor TrendMicro's HiJack This! can get rid of the virus. Anyone have any suggestions or advice?