Oh, a little note on this, when I sent the bones back to their reference position or "zero-pose", I noticed that a few of the IK targets were a little away from where I think they should have been. This may inadvertantly cause the odd behavior in your number 10 chain. It's just a theory at this point though and take it with a grain of salt, but anything off looking on a rig of this complexity could add up I suppose.
And one last question before bed time, was the mesh made in Max or Maya or something? It has an interesting mix of tris and quads and it might help to clean up the arms and make it all quads, but it's not critical or anything, it would just speed up renders a touch I think annd maybe with some smoothing behave a little better too. Just thinking out loud...
