Looks like inverted normals to me. Try selecting the black bits with the Grouping Tool and invert those normals. Then see (start with one of them to verify that this is indeed the cause) what it looks like rendered :o)

Try this tip:

http://www.keindesign.de/stefan/poser/firefaq.html#8

(#8 on Stew's Firefly FAQ.)

It looks as though you may need to tweak the minimum displacement bounds for Firefly, too.

It could also be double-sided polygons.
Lines in Poser-4 renderer, big square blotches in Firefly? If so, that's (probably) double sided polys.

Neither of Poser's renderers like 2-sided polys, especially if there's a texture attached.
The reason seems to be that the renderers are expecting single sided polys (so that they know "which way is out"). With 2-sided polys they have a hard time making their minds up, and keep changing sides.

The "displacement" trick in Firefly works 'cos it creates a distinct difference between the 2 sides. Alas, nothing can be done for the P4-renderer (AFAIK).

The only permanent solution is to import the object into a 3D modeller and make it 1-sided there (and then check that all normals are facing outwards), and re-export.

Cheers,
Diolma

Thanks guys for your advice. I'll give it a go.