Would it be possible to see how you have divided the mesh? Assign different materials to the head, jaw and neck then do a screen shot. Try setting the curve dial for the jaw to zero. I have also seen some oddities with the end of a curve chain. Did you rotate the eyes? If you have not yet set up the eye joints then this will have an effect. See how the eyes are done in a standard Poser figure.... ummm I'll keep looking at it :)