Hardware failure or virus??

Hello,

My (vista) computer runs great except for this one little problem.

Every now and then, it will randomly shut down and display a blue screen with blurry words on it. It seems like some sort of error message, but it takes up the full screen and only stays up for a few seconds (not enough time to even get through the first short paragraph).

Then, the computer will restart, prompting me to run startup repair. Startup repair runs for about fifteen minutes, alerts me that it cannot fix the problem, then shuts down my computer.

Then (and sometimes this next part will just happen if I'm turning my computer on for the first time, without the blue error screen), the computer will begin to turn on, and windows will begin to load. Just before the little progress bar shows up, the screen will go black and a yellow line will run on the right side from top to bottom. The computer will not load past this point, and the only thing to do is restart the computer again and again until it decides to load all the way, which it eventually does.

HELP ME :( :( I can't figure out if it is a virus or a hardware failure. Virus scan will not find anything, and I can't find any information about this online. Thanks so much--