Why do registry cleaners detect a plethora of registry errors even on newly installed Windows OS (without installing anything else) ? I realize such cleaners can mess things up (always make a backup!), but it cannot be true that all or even most of the errors registry cleaners find are actually valid. Is MS not aware of how messed up their Windows OS registries are? I am sure they have heard and use CCleaner or the best registry cleaner there is - jv16 PowerTools (as long as you don't use the Aggressive Mode, which can seriously mess up your PC). I noticed both CCleaner and jv16 PowerTools find a ton of NET Framework-related registry errors if used immediately after Windows 10 installation. In my experience, even on my rig, running light/moderately aggressive scans and compacting registry later improves performance (responsiveness) and can actually fix problems.