My Dell Optiplex 3010 won't start up when there is no monitor connected to it. When the monitor is not connected and I restart the machine, or shut it down and boot it back up, then it does not boot into Windows. If I then connect a monitor to it, all I get is a blank black screen - no error messages. When a monitor is connected, these problems do not happen at all.
The only reference I can find to this problem is in this thread on the Dell support forums but there is no definitive solution posted. Someone did point out that the problem is likely with the added video card and they suggested to change the video adapter settings in the BIOS, however this hasn't helped because I found no video settings at all in the BIOS.