It's almost definitely a shadow issue. I ran into a similar shadow flickering problem with Poser several times before. I "fixed" it by increasing the shadow map size (in some cases dramatically), but that also increased render time. Ynsaen is also on to something that increasing the scene's overall scale may help solve this too. I haven't tried doing that. Using Raytrace shadows will solve it as well I'm sure, but then you're talking a render time hit again, and the risk of possibly not getting the soft shadow effect you desire. I hate to say it, but this is one reason I gave up on rendering animations directly in Poser. Results are often too unpredictable to trust. Hopefully, this isn't a commercial project. ;-)

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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.