The Windows registry is a complex database that programs and hardware use in order to store important preference and settings files.  The registry can be written to at any point by software and hardware, and typically this happens upon installation and any time you change certain settings.  The problem with the registry is that entries tend to be created but never removed.  In order to thoroughly clean out the registry you’ll need to use the best Windows Registry Cleaner Software you can find.  There are several good programs out there.  One of my favorites is RegCure, made by ParetoLogic software.  ParetoLogic has a 100% satisfaction guarantee.