"3D-Mobster- don't take this the wrong way, but your box has way too many polygons.  If that's supposed to be a basic 6-sided cube, why are there so many poly around the corner area? This is probably why Poser is getting confused about how to render those polys"

hehe i totally agree why you say that, as it looks like a 6 sided cube in the render :D But actually its a huge roof and that is just a corner that i have zoomed in on. The big square in the top of the image is actually further down than those making the corner, which are actually a wall. Guess i should have considered that, as its a lot easier when you know what you are looking at.

 This is from the other side with shadows :D

So it makes a bit more sense.