Most times, when I boot my PC, even though I can hear the noise from the fan, nothing appears on my screen but the monitor's message "signal not found". Of course I have already checked the screen cable. There are times when the computer boots just fine until I log in my account (or the second existing account) and then the same thing happens. But there is something even more peculiar. Once I log in (and oddly waited until most run-ups are executed), the screen blacks out. The tower keeps making its tower-noises, so, thinking that the problem affects only the screen, I tried pressing the windows logo key, the up arrow, enter, right arrow and enter, but the noise continues! As you may have already noticed, that sequence of keys should have shut down the computer. The problem is that the computer stops responding to anything I try (including the reset button on the tower), which leaves the only option of plugging it out –a rather unorthodox way of dealing with computer problems-. Since nothing indicates software problems I haven’t ran a virus check after I noticed the above.

I would suspect your video card or if you don't have a video card, the video interface on the motherboard. You can buy a VERY cheap VGA card to test this. Rule #1 Good computers don't go down. Rule #2 There is no such thing as a good computer.

I agree, probably the video card but, just in case, do you have either a second monitor or video card that you can install to test with? You should also open the case and reseat the card too.

Have you tried starting in Safe Mode? then look in Event Viewer to see where the system's falling down. As it's occasionally booting I'd suspect you have more than one issue so starting with the video card is a good idea - also check that everything else is firmly seated as well. "I know that I'm mad - I've always been mad..."

sign up 4 free at http://s13.invisionfree.com/computer_gods as there is heaps of talk about this problem