One problem is that you're using AO on the materials as well as the scene light. Should be either or. Basically, you should use either the AO node on each material (which will allow you to adjust the parameters individually for every object), or you should use it on the diffuse IBL light without any AO nodes on the materials, which would distribute the AO over the entire scene in the same way. Using both is a double whammy, and one is just going to cancel out the other anyway. That said, it looks like a bias problem. Try increasing the bias.

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Tools :  3dsmax 2015, Daz Studio 4.6, PoserPro 2012, Blender v2.74

System: Pentium QuadCore i7, under Win 8, GeForce GTX 780 / 2GB GPU.