Be very careful with this one! It is very aggressive and will wipe out your hard drive cleaner than a whistle, including bookmarks, documents stuff,etc.
I should know, I have it and I payed the price for not digging a little deeper into it, of it's potential!
Also as an alternative try installing Ad-Aware from Lavasoft.They have a free version with limited capabilities, and it's pretty good at finding malware. Along the way you may want to try RegCure, a Registry Cleaner/Fixer with good potential.
I had Ad-Aware and ran it now and then but was having troubles with something, and I gave my ISP control over my computer and the tech took it off. It's not as if I couldn't have done it myself, they think everybody is dumb I guess. Later they tried to sell me theirs, I installed and looked at it but never ran it. Plus they wanted another so much a month for it. So I told them to forget it, PC Fine Tune or something. CCleaner does a pretty decent job, it freed up tons of space on my C drive, have only run it twice but no problems that I'm aware of afterwards. So I'll just kick it around and not do anything hasty. I really need to be phasing things over to my imac but I'm not used to it so there it sits. I can do everything I need to do on my PC so fast because I'm so habituated to all my tasks now even if it has its quirks. Uploads are a breeze, things like that I'll have to learn all over, slow me down to a crawl.