This problem could be related to a game controller (joystick/gamepad) attached to the PC that the game is having trouble recognizing.
This game has support for one controller, the Thrustmaster Firestorm Dual Analog 3.
If you do not have this controller and are having trouble reassigning keys in the options menu:

• unplug the game controller from the PC
• reboot the system.

Once Windows comes back up, try running the game again.
You should now be able to remap the keys without problems.