It cannot be the reason. DOSBox is emulator - it doesn't use video (or anything) "as is", but emulate VGA or something. Well, theoretically speaking, it can be non-compatible with your video drivers (even if I never heard of it), but in this case DOSBox itself wouldn't work, not game.
So there could be 3 reasons.
1. Something wrong with the game itself. Did you try to re-download it?
2. Something wrong with the game settings. Try to change it, if you can.
3. Something wrong with the DOSBox settings. Check .conf file with text editor, and pay attention to "machine=" setting. It must be one of SVGA modes (svga_s3 is most compatible, and default, I believe).
If nothing will work for you, I'll check the game myself. At home.
