Wow!! I am now totally confused. I downloaded ccsetup531 onto my newly built computer, but after reading this I think I'll just delete it and will not bother to install it at all. EVER!! I don't have a clue or any understanding of what I've read here this past half hour but it sure doesn't leave me with confidence in CCleaner. I'm more worried now than I was before I downloaded it. It sounds like if you run the wrong thing in CCleaner you can cause all sorts of issues with the computer. Glad I came here before installing it. Thanks for the heads up and I think I'll just leave CCleaner right where I found it.