Some models do that when exported from another application and the only way I know of is to rebuild and reanimate the model.
It could be the skin affecting this as it shouldnt matter at all where the model came from.
The effect could be happening through 'groups' mode in skin settings, I dont know.
I tried something similar with the character model from 'Projected Texxtures' thread, same prob but I didnt see any point in follwing it thru because it was some one elses model
