resolution problem

i got a macbook pro with a wide screen
my problem is when i try to put enemy territory to 1280x1024 the game gets bigger than the screen
its because my screen doesnt support that resolution
the problem is that i got a x1600 ati that supports even a 2048x1536 resolution but it goes off the screen
the only resolutions that dont go off the screen are the wide screen resolutions
1280x800 1440x900 etc
i tryed to use r_customwidth and r_customheight to change the resolution myself
well sometimes it works sometimes it doesnt and the image of the game gets again bigger than the screen
i think that it has something to do with some logs that r in the game ... i think