At work here we have a 22" Averetec All in One PC that seemed to have a bad video card. With the bad vid card, the screen would show a lot of blue lines and distorted pics. The video card was a nvidia 8600GT. Well, we replaced the video card with a nvidia 9300, and now the only way to get video is thru an external monitor. The pic thru the ext monitor looks great. The built in display shows nothing. Any ideas what may be wrong?