set vid_fullscreen "1"
set vid_mode "19" <-----
set vid_grabmouse "0"
set vid_gamma "1"
set vid_height "1920"
set vid_width "1200"
thats the way my files look and it works!
set vid_mode = your screnn res. number
{ 1680, 1050,= 18 },
{ 1920, 1200,= 19 },
{ 1400, 1050,= 20 },
{ 1440, 900, =21 }
mfg stroemvall