@blacknight Just becuause there appear to be no problems does not mean that it has not deleted valid registry keys. You should check the errors it finds before letting it delete anything. Or better yet, don't use the registry cleaner.
So.... I checked at the beginning, for a while. Since I didn't find errors, I stopped to check. usually i use registry cleaner - this or another - after a program uninstalling, and then I check the registry manually. For every bad event, I have always recent disk images.