adware and spyware progs dont clean out the "dead files" that ccleaner does.   Simply, when you open it up, and before you scan there are two tabs.  You can uncheck the one for "registry" so it doesn't touch it.   I do this generally because ccleaner can (and often does) wipe out SN's of programs so you have to hunt them down again and reregister serials, its a PITA