For some reason, my computer randomly shuts off without warning. It doesn't shut down as if you were to go to Start > Shut Down, but it just shuts off.

Nothing feels hot, and it didn't smell like anything was fried. I cleaned the dust out of it and at first I thought it was just over heating. That may still be the case, but I'm not 100% sure of that...

Sometimes when it shuts off, it won't even turn back on. I have to flip off the power supply switch in the back, wait awhile, then turn it back on. I really hope it's not because my power supply is crapping out on me...I just got it new a couple months ago.

Right now, I have the computer shut completely down, power supply switch turned off, and the monitor turned off. I'm going to wait until the morning to turn it back on.

I don't know why it is doing this, and I really really hope someone can help me out...

I'm using a 500W power supply.

Please please help! It's my main computer with all my stuff on it (games, pictures, etc...).