My friend's Dell desktop recently started slowing down and wouldn't log off. It just stays on the logging off screen even overnight. I can boot it into Windows 7, but it will only last for about 10 minutes before it becomes unusable. It will also boot in safe mode.
So far I have:
reset the cmos
ran hardware diagnostics that comes on the PC
used a clean boot
ran malwarebytes and mcaffe in safe mode
I cannot find any problems, but still it won't log off!