To add to my experiments into this problem, I replaced the terrain map I was using with a flat box for the floor. The ball then worked perfectly, as did the car demo I was originally working on.

Thus, the problem seems to come (somehow) from the terrain map I was using. I still have no idea what the problem is, but at least now I can bypass it for the time being....

That being said, any help solving the root of the problem would be greatly appreciated!

-Doug