My second LCD Screen does not get signal - help

I am in trouble using my new MacBook Pro. I was recently supposed to show my customers images on a larger screen using a projector. It did not work. (Customers' PCs worked just fine.)

When connecting to a separate screen or a projector I do not get any image; but a message: "Cannot display this video mode" or "No Computer Input". What might be the problem? I have tried to change the resolution, turn Mac and screen on and off, detach peripherals... Same results whether in the office or out.

I have MacBook Pro; 2.2 GHz Intel, 2GB 667Mhz; Leopard, wireless mouse and keyboard; plenty of HD space left.

Yes, the adapter is screwed in place tightly when using VGA projector. My office 2nd screen has been working fine previously with my MBP, not now, however.

Earlier I ran the hardware diagnostic with Leopard disc. No fault found. The 2nd screen worked fine after the test; but, then I lost it again (Cannot display this video mode - message)

I got the LCD up and running after doing Apple software update!?
Yesterday the LCD worked fine until I closed the MBP screen and put the machine to sleep. This morning the 2nd screen was black with the "Cannot Dispay This video Mode" text.

Is this something to do with the Sleep issue?

An elusive problem but I need to get it fixed in order to meet with my clients.

Please help.

 

I have tried many different resolutions and played with mirroring. No success! Note that no setting changes were done prior to losing the 2nd screen. The only event is the Sleep. Then when waking the MBP up the 2nd screen is lost and will not come back. No matter what I do: setting changes, reboot, dicsonnect all peripherals... The only times I got it back were: doing hardware check with OSX disc and SW update.