What svdl said. These problems all came in with Poser 5. Poser 6 includes fixes for many of them, such as the "normals forward" option.

I suspect you've experienced at least some of them, perhaps without realizing it. DAZ's MAT files do not work correctly in Poser 5. Some recent items have P5-friendly MAT files, but most do not. They apply the texture map, so you may think it's working right, but if you go into the material room, you'll see the bump map is either not attached, or attached to the gradient node instead of the bump.