At first glance it looks like the inner and outerlayer of the hair strips are mixing with eachother at some areas. This also happens to be the area where the problem occurs. It then looks like that as soon as you tilt the head the simulator gets confused at this point and only calculates the outerlayer at that area, with the result that the inner layer pushes the outer layer out.

You said that you used MD2 to create the strips. MD2 simulates differently as the clothroom in Poser and probably has no problem with the overlapping layers. I wonder if you can get the outer layer not to touch the inner layer would make it work. I tried to create a new group for the outer layer, but that is pretty difficult if not impossible in poser because of the overlap. If I had that group I could have moved it away from the inner layer and test it that way

I am going to do some more experiments tomorrow after I get back