If you have several known and unknown issues, starting over is often the best thing. Yes, there is pain involved but the end result is that you have a machine that is factory new again. Trying to repair/trouble shoot things like this takes more time than you sometimes realize.

I've sort of been where you are now and lived with a somewhat ailing PC for quite a while. Once I bit the bullet to start over from scratch, I kicked my self over and over for not doing it sooner.

If you do decide to start over, don't forget to save your data (music, photos, etc.) to a 2nd drive/CD's/DVD's.

Best of luck!