dga, wine, and a tnt2

[Nix N. Nix]

I've seen the same problem with a TNT2.  This is how I solved it:
I created a screen in X that sets the server to the exact resolution 
required by the game:

Section "Screen"
Identifier "GameScreen"
Device "nVidia Corporation|NV11"
Monitor "My Monitor"
DefaultDepth 24
Subsection "Display"
Depth 24                <- or whatever resolution the game requires
Modes "640x480"         <-
EndSubSection
EndSection