Hello, I have a problem with my PC. It worked perfectly an hour ago. I was just browsing the internet when the screen went black. The PC didn't turn off. By the sounds it made everything seemed fine, so I tried to reboot it. When I rebooted the screen remained black, but now the video card's fan was making an unusually loud sound. I opened the PC, cleaned off all the dust and tried again -nothing; still the loud fan. My guess is that it's my Nvidia 8800 GTS (which worked perfectly for 2 years) or the motherboard. But the video card seems more plausible since it gave me signs of a malfunction a month ago with the screen occasionally going white. Thanks.