I don't know if this is similar in origin, but I sometimes have a problem where imported OBJ meshes randomly change colour in Poser - just moving the mouse around is enough. Unfortunately the effect doesn't render, or I could make a fortune doing psychedelic animations. Not. :)

I haven't worked out exactly what causes it, but it's related to material definition in the OBJ file. The effect can be fixed by opening in UVMapper and re-saving. I don't think I've ever tried opening the material room on one of these, but next time I get one I will.

It may be associated with the usemtl statements, in other words. Les, have you tried importing the injected geometry on its own?