Help: Can't run start up repair or safe mode.

I have an EMachine that is a few years old. I've always had issues with it but I've usually been able to fix them by a simple google search but this is beyond me.

I'd been busy and I mostly use my desktop for gaming and music, so I hadn't even bothered to turn it on in a while. I went today to go play a game and when I powered on and came back, the machine was off. I wasn't alarmed and simply turned it back on, and got the usual 'interrupted during start up' message. I clicked to start windows normally, and before the windows logo (with the green loading bar) popped up it shut down. I then clicked 'launch start up repair' and the same thing happened.

Eventually I ran through everything I could think of, and looked it up on the internet but nothing is even remotely helpful. I used F8 to get the more advanced options and everyone of those has the same result, though a few allowed me repeatedly to see the green loading bar screen for about a second. I opened the case and confirmed all of the fans (processor, power supply and video card) are all working properly. There was tons of dust in the case, but nearly none on the actual fans. The motherboard and hard drive don't have any visible damage that I could tell (I've worked scrapping computers so I have a decent idea of what its supposed to look like).

Even if I had a back up of the files I'm still screwed because I don't have the money to go buy or build a new computer (college student on a limited budget). I'm less worried about my files than a working computer, I can get most of the music and game files back with a little work and some help from my friends. But I need that computer to be working cuz I have programs on there that I need for school. Is there anything that can maybe help me?

 

Immediate shutdown can be LOTS of things --most of them completely unrelated to Vista (which is what we support here). Some of the more obvious would be:
1) general motherboard failure
2) CPU (processor) failure
3) System memory failure
4) Hard drive corruption -- mainfesting in Windows being unable to load or crashing during startup.

You can generally rule out the first three of these if you can run another OS that doesn't use your hard drive -- which you CAN if you do the following:
1) go to the link below, download and burn the Ubuntu CD
2) Boot using that CD, choose the option to Try It, not to Install it

http://www.ubuntu.com/desktop/get-ubuntu/download

If that goes to a desktop (takes a few minutes) and runs OK for awhile, then it's most probably the hard drive that is the problem.