What O/S?
Use MSCONFIG to disable the startup group items.
Norton has a free 15-day trial of their A/V software for download.
Download Norton, update Ad-aware's refernce file.
Then run both Norton and Ad-Aware
If either of them give you any shit, run them from safe mode.
Tell your buddy not to be a dumbass and buy some A/v software and keep it up to date.