Think I have a virus!! Can't System Restore! + other crap

well, i cant use system restore for some odd reason. Also this morning when i restarted computer I got A CORRUPT FILE error ( i forgot name) c:voice or volume idle information or something. Ive also been getting bogus missing files in system32 folder. The XP i used was a sealed copy, said my brother. RAn full system scan with norton twice today, nothing??!! My brother had a bad trojan on his old computer which wouldnt let him use system restore among other things, but I dont know!

First of all, if you have a virus you need to disable system restore. Leaving it on leaves viri a place to hide in. Next thing to do is to update your Nortan to the latest definations, then boot into safe mode, and scan. If it comes up blank, I would try scanning with a bootable linux, or downloading AVG and scanning with that. If that also comes up clean, I would do a spyware scan, and if that also comes up clean, I would look into reformatting, as it's going to be more trouble than it's worth to try to fix it.