Grimm's post in Black noise on object problem was marked as the answer
I had the same issue with Blender, in that if you load an object (I was using obj) that has bad UVs applied. The fix for me was to tell Blender not to export the UVs as I hadn't created any. The other fix is to save the project and then reload it (I'm not sure if you need to restart 3D-Coat or not). Once you do that it should work fine.