External Display Problems with macbook pro please help :-(

Hey Guys
I have recently bought a new external monitor (Samsung Syncmaster 245b plus) for my 15" MBP-2.4 GHZ mid 2008 model running leopard,

But for some reason the display panel in the system preferences is not giving me the option to run the display at 1900x1200 60 HZ or any other resolution above 1024x768 on VGA and DVI doesnt event work EDID problems i think

And after messing around with switch resX the display wont even turn on anymore on VGA or DVI the integrated screen flashes twice but nothing happens!!.

I have installed windows on Boot camp and the screen works fine on VGA at 1900x1200 60 hz. So how do i make this work on a mac osx?
Is there a way to manually set the resolution? I am freaking out :-(

Any help is appreciated.

Thanks

John

 

Yes, all firmware is updated and the resolution is supported by the nvidia 8800GT that is on the macbook pro. And it already worked when i used windows on the macbook, so i think its a leopard issue.... Any help?