the only guess I have right now is that your monitor doesn't supports it. Anyway please do the following: run MA, switch to the highest resolution, exit MA(if possible - pressing Alt+F4 might help) or reboot. send ma.log to
support@massiveassault.com with a brief description of your problem.
For now you can play at high res as following:
1) Set your desktop to highest resolution possible
2) Run MA go to options and select a WIndowed mode for highest resolution. Everything should be OK.
BTW: I only play in windowed mode - it's much more convenient for multiplayer.