Hi I have had to replace hard drives problems on 2 computers. I reinstalled CCleaner Professional on both. CCleaner, accepted the key, worked on 1 computer, on the other CCleaner would not accept the key you sent me. That same key worked on 1 but not the other. I have uninstalled, reinstalled, downloaded new CCleaner and installed it. I cleaned my registry after every uninstall. How can I resolve this problem. I had purchased CCleaner Professional a few years ago and like its function. I am using windows 10 (legal version from ms) on both computers. The same software exist on both computers. These are very basic computers. CCleaner Professional did work on the 2nd before I replaced the hard drive. Please help me and give me instructions to fix this problem Ask me if you need more information. Thank you.