My son has a couple of old Compaq desktops that he uses for work. And when he boots either of them up there is no video at all. He thought he had a bad monitor, but the monitor works fine when hooked up to his bosses PC (which he is borrowing for the time being). Both these computers have integrated video on the mother board. When I brought them to my house to check out I hooked them up on my own monitor and keyboard and mouse. They came up just fine. I had no problem with the video. Whenhe takes them back home & hooks them up with his monitor and keyboard & mouse they don’t have video again. I know in the past in my position as tech support & network admin I have had problems with PC’s where a bad cable or bad mouse or keyboard would cause this problem, and I had to unplug the mouse or keyboard to start booting the machine till the video came back & then plug in the mouse or keyboard again while the machine booted. Have you seen a problem like this before? What could be causing this?