I've been creating my first set of armor for Skyrim using 3dsMax 2012 and ran into a strange problem I just can't get my head around.

Equipping the helmet (closed helmet to replace the entire head) sometimes just removes the head:
I created a new character, saved. Went to bleak falls barrow where I placed my armor. Equipped it: works like a charm. But once I save and reload again, helmet and head are gone. Saving+reloading a second time will make it work again, and so on.

http://abload.de/img/ingame01qrks9.jpg is the thing ingame (left: helmet equipped, not working - middle: helmet unequipped - right - helmet equipped, working)

See the red/black cloth collar on the cuirass? This part is supposed to be hidden once the helmet is equipped, hence it is set to 30-HEAD. Basically I set it up just like it is commonly done with the forearm or calves sections that are hidden once the character has gloves or boots equipped. But it just won't work properly. http://abload.de/img/cshelmetiikp6.jpg is the helmet in the CK.

Yes, the 30-HEAD biped object from the cuirass AA is checked. If I unchecked it the collar would always be hidden and the helmet always working. But that's not what I want, of course.

I also tried to stick the helmet to HAIR instead of HEAD, at least the helmet won't be invisible now. But the problem actually still exists: after loading a game, everything looks fine. Save+reload and the collar will appear (along with the helmet), even if it is supposed to be hidden. Save+reload again and everything appears to be fine as again. This is reproduceable.
I just don't understand why the same system works fine with Boots and Gauntlets but not with helmets.
What about the priority setting? I've been using default settings (5 for cuirass, 10 for everything else) and changing them doesn't seem to be helpful either.