Comment 4 for bug 585898

Although I can't check for time reasons now, I strongly suspect this line (pkg/common/Engine/PartialEngine/RotationEngine.cpp:62):

state->vel=state->angVel.cross(l);

As you recall, Eigen doesn't handle cross product with zero vectro specially; if angVel is zero (at the beginning), state->vel will be NaN.