regedit.exe on boot

Every time I boot Windows XP Pro SP2, regedit.exe appears in processes in task manager and takes end process twice to kill it. There are several viruses out there that do this I have found, but when I look at the information as to files the virus installs(system32/regedit.exe), and registry changes they make, none of them match up. I have run Norton scans, Ad-ware scans, etc. to no solutions. HELP!!!!