The older 1.41.544 works better than 2.0.500 on most machines. The 2.0 bugs (for example, not cleaning tem interenet files) have apparently been worked out in version 2.01, which should be availalbe today or Monday. Check the download/versions page for what's been fixed in 2.01.
QUOTE(Pfipps @ Sep 27 2007, 12:09 AM)

In Vista, CCleaner 2 is definitely better than the previous version...the Registry Issues cleaner no longer breaks certain programs and
it now cleans the "recent files" in Vista...for two examples.