Just finally got around to trying this game, and had the same problem (it acts as though an erratic joystick is attached, even though nothing's actually attached). On the Linux version, the SDL-2 library was the problem: To fix it, I just removed the supplied libSDL* libraries in game/Linux/Bin/lib, so my system versions are used instead. It doesn't look like the Windows version even uses/supplies SDL2, so this probably doesn't help you at all.

Frankly, I hate games that auto-detect joysticks and then assume you want to use it. On Linux, at least, I had to completely disable my previous laptop's accelerometer, which is presented by the driver as a joystick-like device. The game should really be configurable as using the kb+mouse, or at the very least which of the joystick devices to use, if present.

edit: clarified a bit