I dont know, but alot of reg clean programs screwed up my system.
The only one that didnt was Norton System Works 2004 NortonWin Doctor, and i use it in the 1 button checkup. It finds alot of bad reg entries left over from junk i uninstalled.
I actually know that Norton's software has some temp files and stuff that it can only work with, because i used a temp file cleaner and the Norton programs all glitched up and stuff. weird.