I'd check your mesh in NetFabb or something. Every time I've had a problem like this in Z-Suite, it ended up being a problem with my mesh. Maybe not the case here but worth a shot.
Funny, when I first read "Faces appear unwanted in Z-Suite" I had this image in my head of Rafal's face suddenly appearing on the screen :lol:
I'd be willing to bet quite a large sum that your mesh is the culprit (note the bizarre triangular patterns). Everybody here loves netfabb, but I've had meshmixer fix meshes that even netfabb wouldn't touch.
Funny, when I first read "Faces appear unwanted in Z-Suite" I had this image in my head of Rafal's face suddenly appearing on the screen :lol:
I definitely got a mental image of a 3d face being added onto the part. :D