Good'n'bad news!

I tried the workaround I was told (downscaling the model) and scaled the model that's used as an physics entity to 40% of its original size and yes it worked. The model was bouncing and becoming stable without a crash. Then I "kicked" the model with the space-key (just as it's ment to be in the earthball-example) and the engine crashed again.
I also got a second crash which is easily reconstructable: just change the config of the model from PH_BOX to PH_POLY and you'll see that the model gets immediately stuck in the ground after falling causing a engine crash just again.

Maybe you could take another look at? It's even possible that it's just the same bug in other clothes.

Cheers,
Chrisu.