OK, I think I've figured it out ....

I assigned a COLLISION NAME of "Base". Apparently, the Interactive Framework uses this name for some internal purposes, because as soon as I changed it to "BoxTest", everything was working just fine.

Duhhhh
I haven't figured out yet what the Interactive Framework does with that, but it screwed it up ...
Now, I just need to figure out why the boxes wobble/jiggle instead of just standing still

and why setting the cast shadow flag causes the textures to flicker and why it produces ugly shadows (looks like some more reading and searching

)....
Cheers,
Andreas