[ODE] LCP internal error causing break of motor constraints?

[luca regini]

I a chain made with universal joints. I want the chain to be stiff so i set
desidered velocity = 0 and Fmax to a suitable value.
The chain is controlled at its bottom with a slider.

I set directly the slider (motor) velocity to move the chain.
At the beginning the chain moves rigidly but then, as soon as it touches  a
mesh in the environment that makes it bend, the motor constraints don't work
anymore. I see that i get an LCP internal error on the collision. Maybe this
is the reason??

I can attach a small executable if someone is interested.

Greets