No registry cleaner is safe and some of them can break your system,: see
So based on this article this so called expert admitted windows registry leaves orphaned keys behind, and removing will fragment registry like it does a hard drive. Since most of us know that registry problems occur from large amounts of unwanted data, we know that those orphaned keys need to be removed. I find it hard to believe that it only speeds up a user search of the registry only. If it has noticeable speed improvement for a user search what do you think it does for windows when it has to search the registry? Again I say apply a little common sense here. The more bloat, or orphaned keys, there is the longer it takes Windows to search through it. Here is a page that list what causes registry errors. http://www.ryansccs.com/Basics-Windows-Registry.html and here is on for registry defrag info. http://www.thewindowsclub.com/registry-defrag-good-or-bad Can cleaners remove something that it isn't suppose to? Yes, but that is why it has a backup feature so you can restore the missing keys. If you are that worried about causing harm to your computer, then you probably do not need a computer. Installing software can be harmful. I think this is the reason you make backups. Believe they work, or don't. It is all just someone's opinion. I base my opinion on the fact that when my computer starts running sluggish I can clean the registry and it fixes it, and yes 3 different anti virus programs give it a clean bill of health.