MajorGeeks has a warning about Steven Gould's "CleanUp! 4.5.2". In some configurations of Windows XP, it finds certain required system files and deletes them if you have "Scan local drives for temporary files" enabled and you need to use Microsoft Office 2003. It has a few other notes too about Outlook Express, Windows XP Professional 64 bit edition, and its list of cookies is case sensitive.

http://www.majorgeeks.com/CleanUp_d4895.html

Also, it says that it supports Windows OS through XP, but it does not say that it supports Vista anywhere that I looked:

http://www.stevengould.org/index.php?option=com_content&task=view&id=167...
http://stevengould.org/software/cleanup/WhatsNew40.html
http://stevengould.org/software/cleanup/WhatsNew45.html