Computer Is Shutting Down Randomly

I'm having a serious problem with my computer, and I feel that I have to type this as fast as I can because it's been shutting down very randomly lately.For the last three or four days, my computer has been completely dysfunctional? I suppose. At first, it just wouldn't turn on. I left it for a bit, and it actually would turn on, but it would run so incredibly slowly. I could barely open a program, and when I could OPEN them, they wouldn't run at all. After letting it sit for about two days, I turned it back on, and it works pretty okay for the first hour. The second hour it'll slow right back down, and then spontaneously shut down. I know this sounds like an over-heating problem, so I bought a really intense heavy duty laptop cooling fan to put under it. That doesn't help.

My laptop DOES get hot, but nothing significant, especially with the fan. I figured it might be a virus, so I installed Kaspersky. Kaspersky runs fine, until I get to about 83% and it will continue running, but it will never go past that 83%. (I've let it run for almost 6 hours). I tried Kaspersky in Safe Mode, but my computer spontaneously shut off then too.I have Word 2007 installed, and it won't save any files. It just says, "Word Cannot Save Due To A File Permission Error". And just doesn't. Playing video is useless, because it just stops halfway through whatever media is playing. I've down two system restores to two different points further away, and that hasn't stopped it either.