Can't play at 1280*800 fullscreen

OMG I fixed it in 4 steps:

1)Delete system.dat from Documents/Crossfire folder

2)Open the game and play, it should go fullscreen, but if it does look "fugly", read next step

3)Change your desktop resolution to match in-game resolution

4)Step 2 is your friend

This method should work for any "conflictive" resolution