Go to <CC installaion folder>\Base.rte\Settings.ini and try to set
Code:
ResolutionX = 1920
ResolutionY = 1080
Fullscreen = 1
NxWindowed = 1
NxFullscreen = 1
If you're on Vista/7/8 you'll probably have to go to %userporfile%\AppData\Local\VirtualStore\Program Files\Data Realms\Cortex Command\Settings.ini