"3D-Mobster- Sorry, but I have no idea what you're talking about. "

Here is an example on a large scale where the smoothing goes wrong even though there are nothing wrong with the mesh. Its just that poser doesnt seem to handle sharp edges very well and therefore makes these weird things.

Example 1 the left side is from the preview where you can see some light areas and some weird dark shadows, when you render it the right side, you get bad lighting. Example 2 i have detached each side, which will make poser think that its actually 2 objects and therefore wont try to smooth between the surfaces, even though its one object. 

To me it looks like that is what is happening in your render, my example is just using a much larger object or edge than yours. But as i said whether thats the actual problem im not sure. But i have to say it looks a lot like it as i have had problems with it before, and have fixed it like that. But it doesn´t happens with all objects and why it happens in the first place im not sure. In some cases you can turn off smooth polygons in poser and set crease angle to 0, but it might create problems else where in the mesh. So detaching things seems to be the only certain way for fixing it that i have found at least. 

Both example uses same default poser light and same IDL settings.