As I guessed - the MED solution didn't work.
Firstly I thought it would work because it didn't crash just at the first contact with the ground but it DID crash again when the model (physics-entity) came to a stable and still stand on its bottom.
Strange! I can mail (or whatever) you the modelfile - as I'm just a user of the Sybex Edition (as listed in my profile) I believe I'm not allowed to contact the support.
So, what shall I do?

Cheers,

Chrisu.