Im not much of a modeller, so I dont know IF this is related to the problem,
But open the model in MED, goto "faces" mode, and "edit/select all".

Then roll the 3d-view around until you are looking at the "top" of the head/ears.
See those black marks on the ears? What are they anyone?
Damaged polys, flipped normals, or what? The dont belong but I cant
figure out what they are...