Hello Vincent,
I had wondered about this very issue. The AutoCAD file I added was off origin, far away. I thought I had fixed it and cleaned it up, but maybe there is a hidden block somwhere. I am going to try and clean it up in 3ds Max, reset object origins, then collapse with Xform, and see if that fixes things.
I will also submit this bug, just to get their take.
Thanks for getting back to me! Love what TM is doing!
Cheers,