Hi Synthercat, there are ~500 double faces on each sphere.
Remove doubles and recalculate normals help but still not 100 % clean mesh.
Add Edge Split modifierer, to get better mesh and may subdived 2 applied.
Blender 2.67a + Addon 1.21
Edit: The spheres also very small, this can make problems in Octane too.http://www.pasteall.org/blend/22194