Ayman - I have resolved the error (a silly mistake regarding definition of coordinates for a weld joint). Thank you for your help and please disregard the bug report.

To my knowledge, all of the coordinates defined in my model are also used in the motion file. I have submitted a bug report and attached both the motion and the model files. Thanks for the help.

-Ryan

<t>Hello,<br/> <br/> OpenSim is crashing during my analysis as well. All bodies have mass and inertia except for our ground. I am not inputting results of an inverse kinematics analysis (we have created our own motion file for a class project and I'm inputting this instead) and we have no external f...