If I'm not mistaken this usually happens (if you use wings3D) because you didn't triangulate your model before exporting. If you already have triangulated it but are still getting this error, check your faces again and make sure all face normals are pointing the right way.
A. Don't really know what you mean by my normals being inverted, but in terms of modeling the planks separately: I started with a cylinder and cut it into pieces.
I am starting to get the hang of modeling for mount and blade and really enjoy it, but I'm having a problem. Every model I have made has some part of it missing, for no reason, when I import the model to .brf edit. I use Wings 3d and would really appreciate some help.