I have Acer Aspire 5520g, vista 32 bit. It is about 4 years old and have worked fine for most of time. Two days ago, I tried to turn it on for several times and it shut down automatically everytime after it ran for a few seconds. Sometimes it just shut down without the screen lighting up. I have noticed that if I left the laptop alone for a longer time before trying to turn it on again, it will be on for a longer time to actually let the screen lights up and run. (But never long enough for me to press F2.) Today I tried to turn it on several times and the BSOD came up once, but I didn't get the chance to look at it since the computer turned off right after I saw the BSOD. Then I took out the battery and put it back on again, nothing changed. Then I pressed Alt + F10, but it still does not work. Also, I don't have the Vista Repair System disc with me. I did not install any new software or hardware recently, either. Does my computer have a virus, a hardware problem, or a software problem? What can I do?