My colleague and I are in a client's conference room.

When he plugs his laptop in, and directs his Dell to use "Duplicate" screen, "Invalid Format" appears on the external monitor.

When I plug mine in, the monitor works fine.

We are both using Dell Latitude E6400s and Windows 7. His is a 64-bit machine, mine is 32-bit.

He has had no issues plugging into external monitors and projectors at other clients' sites.

We have updated his video driver from the Dell website. It did not make a difference.

The monitor is a big honking LG flat screen.

Looking for suggestions?

Maybe try adjusting the res before plugging the monitor in. Try a low common resolution like 1024x768.For some reason, it wanted to "force" (for lack of a better word) the dual monitor feature to use the highest resolution available for both, instead of allowing us to set the primary for one and the secondary for another.... Once we clicked through that a bit, we were able to adjust the resolution.

Thanks! (It seems the STANDARD two pieces of ADVICE are always: 1) Reboot, and b) Update your drivers. So after doing both of those, I was STUCK - so thanks!)

rjb