Restart your computer, and then press F8 during the initial startup to start your computer in Safe Mode.
Log on to your computer with an administrator account or with an account that has administrator credentials.
Click Start, Run type %systemroot%\system32\restore\rstrui.exe and then press ENTER:
Follow the instructions that appear on the screen to restore your computer to an earlier state.
If that doesn't help try this.
Faulty Fans, Dust and Grime build up on the Heatsink restricting air flow. I would give the inside of the case a blowout with compressed air. When blowing air through the fans make sure that you physically stop them from spinning, as they may generate power and blow something up. Remembering to ground yourself by placing the back of your hand on the Power Supply Unit and not moving your feet. By not taking this precaution it is possible that you could inadvertantly cause damage to the PC from an electrostatic discharge. Then remove the Heatsink, giving it a thorough clean and reseat the CPU applying new CPU grease. If the Fans spin freely when you give them a spin they are probably OK. If there is resistance replace them.
Keep us informed as to your progress if you require further assistance. ;) :D