" Microsoft does not support the use of registry cleaners . Some programs available for free on the internet might contain spyware, adware, or viruses. If you decide to install a registry cleaning utility, be sure to research the product and only download and install programs from publishers that you trust. For more information, see when to trust a software publisher.
Microsoft is not responsible for issues caused by using a registry cleaning utility. We strongly recommend that you only change values in the registry that you understand or have been instructed to change by a source you trust, and that you back up the registry before making any changes.
Microsoft cannot guarantee that problems resulting from the use of a registry cleaning utility can be solved. Issues caused by these utilities may not be repairable and lost data may not be recoverable.
Before you modify the registry, make sure you back it up, create a restore point, and make sure that you understand how to restore the registry if a problem occurs."
Don't trust me? Head to Malwarebytes blog, and they will tell you why is it bad. Even Microsoft does not support use of registry cleaners