I've used CCleaner since it was still named Crap Cleaner. Never, ever a problem with Cleaning or registry issues. It is such a benevolent registry "cleaner" that very few hard issues are removed. Just benign entries, from my experience, and I do read the entries first, or used to till I became comfortable with using CC. I run so many security features on my network and back-up the reg often. Maybe I've just been lucky. Either way, it is a great little piece of Freeware.
Robert G.