Warbler said:

I don't know if this has anything to do with the problem I was having with ads popping up or not. If I leave my computer alone long enough(usually about an hour or two), it restarts itself. It doesn't seem to happen while I am actively using it. But when I leave it sit there doing nothing for long enough it restarts itself. Any tech savy people here have any suggestions?

Ad pop ups:

If you are on Firefox, go to 'tools', 'add-ons', 'extensions' and see if there is anything strange installed. My just sorted out my parents PC that had 4-5 spy programs installed in there and that's despite having an active anti-virus program.

Switching off:

I had an very old computer that would restart whenever I did anything intensive like render a video/boot up a game etc which I put down to overheating, although I could never be sure. But your problem of shutting down when you are doing nothing sounds the opposite. If it doesn't restart when you yourself are putting additional strain on the hardware, I can't see how it could be overheating or faulty/old components.

Have you tried opening up 'task manager' and seeing what processes are running. Anything look out of place?

Or could something be running in the background? I recently did this (Method 2)...

http://www.pcworld.com/article/241049/how_to_disable_windows_startup_programs.html

...and it sped up my PC about 10% (On the performance monitor). It takes along time to google and readup on what all the processes do, so you can decide if switching them off is safe or not... but worth it.

Try updating all your drivers?

Try restoring windows back to a date before it started happening?

Before ditching the hardware I'd reccomend a clean sweep reinstall of windows and all your drivers and programs. Usually sorts out most catastrophic problems.