Before I attempted any registry edits/"fixes"...I would back up the registry...things go wrong every day.
A good tool for doing such is ERUNT Registry Backup Tool - http://www.snapfiles.com/get/erunt.html
The Windows registry
is a central repository (database) for storing configuration data, user settings and machine-dependent settings, and options for the operating system. It contains information and settings for all hardware, software, users, and preferences. Whenever a user makes changes to settings, file associations, system policies, or installed software, the changes are reflected and stored in this repository. The registry is a crucial component
because it is where Windows "remembers
" all this information, how it works together, how Windows boots the system and what files it uses when it does. The registry is also a vulnerable subsystem, in that relatively small changes done incorrectly can render the system inoperable. For a more detailed explanation, read Understanding The Registry