I have a computer lab with about 26 HP workstations. For some reason I will get a couple of computers a week that after they boot up and get to the windows screen the monitors go black and say cannot detect video input. Ive tried everything you can think of trying and the only thing that I am currently doing to fix the problem is going into safe mode and uninstalling the graphics driver then restarting the machine and downloading the driver again. The computers are hp xw4400 with nvidia quadro fx 560 graphic cards. Just wondering if y'all had any other input on this issue. Thanks.