Yesterday when I was watching hulu my computer froze. Then I powered off forcely. But after I powered on again, only to find black screen. There was nothing on the screen. But the computer could boot successfully because I heard the sound of vista starting and I even could login in. What's the possible problem? Is it because the video card is dead? If it is, can I change a video card by myself? I remember the video card is nvidia, not integrated intel. My warranty expired, so I have to figure out how to fix it by myself.