|Sorry about that, I missed that in #6. Did the computer come with Vista installed then or possibly WinXP? If XP is your Vista DVD an upgrade version?|
Look at the link directly below this sentence to see if a repair of Vista is appropriate.
Do you need to recover personal files prior to performing a factory restore? Factory restore will put the computer back to the state in came from the manufacturer. If you need to recover files there are some methods.
Do you store everything on the same partition?
Link below explains the procedure to perform a factory restore.