Cassidius:After some faffing about, I was able to load the mesh into the costume editor; the actor head WAS enabled in there.
However, taking the tick out and resaving the cos file didn't fix the problem. I went back and reopened the file again, and lo and behold, the enable head tick was back.
Check it out again, this time in Costume editor before saving it, check to make sure your saving it to the game path. In case this is what the problem is and you don't know what I mean, goto the file button, click on game path, click on File again and double check that Game Path has a checkmark on it.
Now save it.
I make that mistake all the time, and know better. Just in case this is your problem, I figured I would post it.