There might be one reason for this William_the_Bloody. Victoria and Vicky 2 and Mike 1 and 2 had many 4+ sided polygons in the mesh. For instance there are two polygons in the eye-backs of 32 sides in V2 (if memory serves me right). In all there were some 40 or more of these beasts which caused many problems with other modelling programs. And while it seems Poser 4 could handle these, it may not have liked them much. Who knows what goes on in the mangled Poser code?
On the other hand V3 is clean of these messy polygons, only having 3 and 4 sided ones. First thing I did was to check the mesh out with UV Mapper Pro after buying it.
Maybe the answer?

Regards
STORM