I am posting this for a friend who is having this problem but obviously can't post this himself as his computer will not boot up. He started having problems after a video game crashed during online multiplayer. The game is Minecraft, which is written in Java. He was able to send me this from his iPad.
"Console generates a huge log about detailing how the java application stub crashed. So I shut down the computer, note, regular, controlled shutdown, not force shutdown. Then when I go to reboot, the HDD boots up, and makes its little boot up noise. The screen is the usual eggshell white. Then, it makes the HDD shut down sound, and the screen goes to black. I tried this three times, same result. Right now, I'm just waiting, hoping that it's overheated or something. Any ideas?"