I had a virus, and now perfstringbackup.tmp keeps reappearing?

Yesterday I had some weird ave.exe virus that included Vista Security popups like crazy, and I think I removed most of it. Microsoft Security Essentials shows no problems when I run a full scan, but an AVG scan still shows part of the virus somewhere, and in system32 folder something called perfstringbackup.tmp keeps showing up. Does this mean I still have a virus somewhere? I don't know too much about removing viruses and whatnot, so any help at all would be appreciated!