AO Artifacts

Hello all

I am trying to bake some ambient occlusion into a model, however whenever I do, it seems to product artifacts. The following screenshot shows the problem.

At the moment, there are overlapping vertices in the UV map, however this does not seem to be the cause of the problem, as the lower half of the bake seems fine, and that also contains overlap. I have also tried modifying the UV map of the top half to contain no UV overlap, however the artifacts still occur. In general modifying the mesh geometry does not seem to help matters.

Any suggestions as to how to create a clean AO bake greatly appreciated.

First thing is to select all vertices and remove doubles (W / remove doubles) then recalculate normals (Ctrl+N)
Attach or post a link to your blend file if this doesn’t help. Screenshots on their own are of minimal use to anyone.