I bought CCleaner some months ago. Cleaned my registry several times. Finally decided to clean my files also. When the screen came back I was unable to do anything. I had to do a hard shutdown. I was unable to get into Safe Mode. I called Microsoft and we determined that the registry was corrupt. We had to rebuild the operating system in place. I am still finding various functions that don't work but have been able to fix them. I would not install this software.