2010 MacBook Pro 3 beeps, black screen of death?

I have a late 2010 MacBook Pro 13". I was playing Minecraft last night, and it crashed. First time ever that Minecraft made it crash. I restarted as the screen told me to, and it didn't chime. Instead, I heard 3 quiet beeps, and the gray screen with the Apple logo. If I leave it sit for an hour, it'll boot, but the screen will go black as soon as I click or hit a key on the mouse keyboard. I still see the cursor when this happens.

I'm running the latest update of Mountain Lion, but my CD is Snow Leopard. I put the disc in, and after holding "C" for literally 5 minutes, it started to boot from the CD. I open Disk Utility, and I repaired my disc. I then decided to check and see how much RAM I have. It turns out that all 4GB of the factory installed RAM is in there correctly and readable.

So what is wrong with my computer. Could repairing the permissions or reinstalling OS X fix it? I'm poor, and don't have a Time Machine drive, so none of my information is backed up.