7800GS fan problem

[sparks]

I have a 7800GW AGP that drives 2 monitors, a Dell 2407 (DVI) and a Samsung 710T (VGA). Last time I tried to play a game, I disabled the 710T so I would have a single monitor. When I did that, the computer would randomly reboot. After investigating, I discovered that the video card fan was not spinning up and was overheating. When I re-enabled the secondary monitor, I could hear the fan spin up immediately. Now when I play, I leave both monitors enabled and I hear the fan, but it is annoying trying to drag the cursor around the screen and being very careful not to drag it to the secondary monitor and disrupt the game. Any suggestions?