Strange problem in my custom helmet mesh mod

[Zurgnunus]

Hey there! I just got back to modding on FNV and have finaly been able to make a custom head mesh, the problem is: It looks good in game, until my character does something or gets crippled, then the head starts to look at the wrong direction and in 3rd person my character starts to fire at the wrong place. Anyone know what this could be?

By the way, the mod is Brainfull and is available at Nexus if anyone is interested!