Dual Monitors -- Can't Turn Off HELP!!

[Alan]

Hi,

I have a Dell Lattitude C840 laptop with an Nvidia video card installed by
Dell.

Whenever I plug into a LCD projector and activate my external monitor the
dual monitor feature comes on and I cannot disable it.

Some times I want to run dual monitor with the laptop (such as for
lectures), however, sometimes I want what appears on the laptop screen to be
the same as on the projected image.

I have tried going into the Display Properties and Settings to disable the
second monitor and when I do all that happens is that I go back to only
seeing my laptop's monitor and nothing on the projector. When I activate
the external monitor the dual monitor feature kicks on again.

It never used to do this and I am not sure what changed on my system.

HELP! This is making it very difficult to do my job!

Alan

 

[Jerry]

You would be better off asking Dell.

 

[Alan]

I would like to avoid calling Dell. Running Windows XP Professional and
the problem didn't always happen. Just recently it started. I am hoping
to get some hints as to what might be messed up.