How many video cards do you have on the PC? If there is only only then right click on the desktop and go properties. Then go to settings open-up advance and set your 1st monitor has defauft. Then apply the screen will go off for sec. this will ask you if you want this setting, click oK. If you have 2 monitor video cards with 2 monitors there is a free proagram that lets you use both at the same time, in fact the way you point your mouse is the monitor that is use. You can even have your back ground on both and spilt the screen if want. Here is the site http://www.mediachance.com/free/multimon.htm
This is weird because everything was working just fine. I have 2 TFT displays connected to my Windows 2003 server box. I have nVidia GEForce 5500 Graphics Card whose DVI-to-VGA adapter I used to extend my primary display (Samsung TFT 17"). I set the second one (Daewoo HL710S 17") as the second monitor with "Extend your display" property in the Display settings. This was working just great for 3 weeks.
Last week I may have touched something on the connectors and the second display since then shows "NO SIGNAL". Of course I checked, tightened and did this again for the DVI-to-VGA adapter as well as the incoming connections.
I noticed that when the computer boots up, the second monitor displays just fine (the Windows 2003 Server logo etc). As soon as the machine boots up the display says "no signal".
I read somewhere the DVI-to-VGA adapter is basically an analog device. But all this was working just fine, I dont know what I touched off for this to stop working. Any ideas anyone?