So... I've used CCleaner for a long time, but didn't know if it's safe to fix everything in the "Registry" tab, because I've had many bad experiences with registry cleaners
CCleaner is a very mild registry cleaner and won't mess too deeply into the registry, it also prompts for an automatic backup before doing it's business (if the option is ticked).
You shouldn't have any problems with it. I use it from a long time and i never had a single problem with it. Like TFT said it does not go deeply into your system.