Something is wrong with my PC, not entirely sure how to fix it.

[Germinade]

So i started up steam and tried to load a game. the game itself doesn't load, so i click it again and a message pops telling me that the game is already running even though there is no indicator telling me that it is. So i try to load firefox, and i realize that none of my applications are working. I cant even shut down my computer. I try to press control alt delete and nothing happens, after about a minute the screen turns black and a box pops up saying failure to display security and shutdown options. I tried a specific boot and disabled all of my start up applications. afterwards, i was able to pull up steam and the internet, but after about 10 minutes the problems started reoccurring. I have tried everything that i am capable of doing, so can anyone help me?

[Legendary old man]

Sounds like a possible virus infection. Do a virus scan with at least 2 scanners. Also check your hard drive for corruption with chkdsk.

[Germinade]

I have done both of those things. Thank you for the suggestion though.

[Legendary old man]

Monitor your processes when this happens as it sounds like one of them might be consuming 100% CPU. Also try a clean boot.

[Germinade]

I ran a clean boot and i think that i have made some progress. everything seems to be running normal

[_I_]

run mbam
http://www.techspot.com/downloads/4716-malwarebytes-anti-malware.html

do the quick scan, fix everything, reboot
then do the full scan, fix everythign again and reboot