External monitor will not display

My external monitor will not display anything when connected to my MacBook Pro. (this is the second incident of this and it will work with other computers)

The computer still thinks the monitor is displaying. When I drag my mouse arrow across to the external monitor's side, I can drag back desktop icons to my laptop monitor. In System Prefs, it says another monitor is connected.

I talked to a tech earlier about this and we tried several things, like holding down command + option + P + power button (or something similar) and it worked, but once I rebooted the same problem happened. He suggested I reinstall Leopard which I did. Everything was fine.

I just installed some updates and now the same problems is happening. Can anyone please help with this?

Thanks,

Joe

Possible work-around?

Frustrated, I've played around with different ways to get my monitor to work and have come up with one:

1. Shut everything down.
2. Turn off and unplug my external monitor
3. Start up my MBP
4. Once the MBP is fully booted up, plug back in the external monitor and turn it on

This has worked twice-in-a-row now. It's not a very scientific solution and is an unneeded hassle, but it seems to work for me...for now.

Good luck.

-- Joe