I have the lastest version of CCleaner and I bring up the registry cleaner. It goes up to 21 or 22% and finds a lot of missing entries but it will contiune past the 21 or 22% and it will cause the computer to become slow and unresposive. I have a old laptop with windows xp home and sp2. I have Zone Alarm sercurity installed lastest version also the last version of CCleaner had the same problem. My laptop has 1gb of RAM and old single-core procesor from AMD.