There are smoothing dials in the figure. Was this figure "smoothed" (Subdivided) in Poser and then you tried to rig it like that? I don't have a version of Poser that does sub-d (I have Snarlgribbly's script, which kind of does that.). However, I would think, and I'm just speaking with no practical knowledge of Poser SubD, that it's "dynamic" and does not actually, permanently, sub-d the figure, since that would mess up all sorts of stuff. It would probably have to hold a reference-figure for the SubD in memory, and the dynamically sub-d it in the display. Such a figure might be able to be saved with a "subd" attribute, but it wouldn't truly be sub-d'd "in real life." In other words: The object file, itself, would not be sub-d. And, since the vertice information is critical for rigging, you might have presented Poser with a problem it couldn't handle, if that's what you did. The CR2 (or saved pz3 file) directly references the wavefront object file, itself. THAT is the geometry that is being referenced,first, before anything else is applied to the geometry/figure according to the CR2's other qualities. (Magnets, rigging, jcm, etc.) If your base object's verts don't match up with what the CR2 thinks is supposed to be there, then you get problems...(Though, some things are not problems at all and the CR2 can, and will, ignore them.)

Sub-D the actual geometry outside of Poser and, preferably, group it outside of Poser, as well. I never group in Poser unless forced to, since I hate the tools it has for that. It should be very easy to do in Maya. Just copy the faces for a group from the original mesh, paste them right back, rename them to the group you want them to belong to, then do the rest of the groups like that. You will export a "multi-grouped" figure mesh and the mesh will NOT be contiguous. But, that's what Poser likes for its basic rigging scheme and it avoids having to deal with the grouping tool at all... which I detest. :)