After some investigations, it appear OZ cant create a S3D when there are more then ~200 meshes (objects) into a 3DS (and it prolly crash too if i used MSH system, since its correct for OZ, but crash during S3D creation).
When i attempted to merge my zone (Well actually, its tunnels from floating islands), S3D creation succeded (Mesh is around 59k poly).
It appear to me OZ is barely limited to 200 mesh during the S3D creation process, i know im the first one to really use OZ, and that for sure a bug of OZ, and not a limitation of the software ...
http://perso.wanadoo.fr/coregn/Everq...Temp/AP027.jpg
http://perso.wanadoo.fr/coregn/Everq...Temp/AP028.jpg