Thanks for the suggestions, guys. Ultimately, I think this is a flaw in the physics simulation -- I ran further tests, and it's possible to get the ball flying at ridiculous speeds. If that ball is the only thing moving, it shouldn't be possible for |v(final)| to be greater than |v(initial)|... unless the mass of the ball is being converted into kinetic energy (E=MC^2 after all ).

I *think* I just need to go with a system of c_move()s. Alas!

It is certainly a flaw in the physics simulation, but when you use a physics engine you just have to deal with such flaws. ODE uses a numerical approximation, which results in such a behavior - called an "explosion" - if parameters are outside its usual range. It's certainly possible to fix this, by adjusting the ball's physical properties as suggested here.

Yeah; I've been mucking with gravity, elasticity, check distance, fps lock, sexiness, mass, etc. I just haven't been able to find any parameters that work for me. Has anyone else run into this problem (rolling sphere) and managed to solve it?