You'll need to tell us a bit about your hardware -- specifically about the age of your video card(s) and motherboard and the type of monitor. My guess is that the game is sending commands that your drivers don't know how to handle, so your system is defaulting to your monitor's default resolution.
I'm guessing that you've already tried adjusting the game's video setting in the launch screen. Have you tried connecting to an old CRT? Or perhaps and old video card?
That's all I can suggest. I hope someone has some more appealing ideas.