I'd do a complete system virus scan before trying anything else. If you don't have an up-to-date AV programs installed, there are free scans online at
Panda and
Housecall.
If you don't want to go that route or if you've already scanned and the system is clean, you can use the freeware
MoveOnBoot which will delete the files and folders you tell it to the next time you reboot.