The Windows registry is a very difficult thing to understand.  Even experienced Windows techies often don’t know everything about the registry.  Most average computer users don’t even know that they have a registry, let alone that it’s often the culprit when you’re having certain computer issues.  If you’re wondering how to clean the registry, then I definitely suggest doing a google search for some FAQs on this subject.  It basically comes down to getting yourself a good registry cleaner software program.  My favorite registry cleaner is RegCure, and I’ve found it to be very easy to use and effective at doing its job.