Baking ambient occlusion gives odd black vortex output? I am having a very strange problem when I bake an Ambient Occlusion!

The problem is very very visible, When I click Bake, it bakes everything and then in the last few seconds it does this weird "vortex" kind of effect. It always starts from the bottom left.

Also, any UV unwrapping doesn't work either (UV unwrap, Smart uv project etc. all don't work).
For some reason this seems to be caused by the wire material.

If you remove it by pressing the - button:



Then it works as expected:



This looks like a bug to me. You might want to consider reporting it to the tracker. I've since reported it here.



Also note that there are some internal faces and non-manifold geometry in your model, which can also result in some artifacts. Try pressing &#9096; Ctrl&#9095; Alt&#8679; ShiftM in edit mode to select problem spots.