It seems when certain keys are held down during gameplay, I can only turn in one direction while going backwards. The keys that do this appear almost random.
Problem is, one of those buttons is the one I want to use as my "Run/Turbo" key.
Does anyone have an idea on how I might prevent this from happening?
Edit: Just to clarify, I'm talking about the first MDK.

It sounds like it could be a limit on the number of keypresses on your keyboard. What keys are you pressing when you are trying to go in either direction? I think alot of standard modern keyboards are limited to 3 buttons being pressed at the same time.

It happens when I press one of the affected keys as well as the down and the left or right arrow. It only happens during backwards movement, never while staying still or going forwards.
Oddly enough, the direction it prevents me from turning depends on which of the affected keys is being pressed.
I'm totally stumped.

Try moving either the run key or one of the directional keys to the other side of the keyboard away from what you are pressing. Now press what you normally press and see if it still has the same problem. You won't be able to use the mouse most likely when you do this but its just a test for now.

I still seems to cause the same problem, whether it's assigned to "run" or not.
The mind boggles.

Does anyone have any ideas? I've been playing this game since I was a little kid. I'm beginning to miss it... :P

If you haven't done so already contact gog support and give them in as much detail as possible what your problem is. They also generally like it if you send them a dxdiag as well.

Thanks for the advice. I'll make sure to do that.