gotoAndStop child confusion

Hi!

I am trying to understand the new order in which AS3 does things, but have run into a bit of an issue.

I have a movieClip called "Walker" which has several children that make up a person, there is a child movieClip called head, body, armL, armR ect. Each of these child movie clips have multiple frames with different varieties of heads and arms and what have you. "Walker" has many frames each with internal body parts arranged and rotated to make the character look animated. My goal is to be able to use these frames to make multiple characters simply by telling the child movie clips to go to different frames (i.e. telling 'head' to gotoAndStop(2) )

I understand telling a child movie to change frames is complex now, but I have used the following function to achieve this.


Over.Walker.addEventListener(Event.RENDER, onRender);
function onRender(event:Event):void {
Over.Walker.head.gotoAndStop(2);
}

On an enterframe I have the code:
stage.invalidate();

"Over" is the name of the movieclip Walker is itself a child of.

As I tell Walker to go to the various frames it needs to I want the head/body/arm ect. inside to change to the frames they need to be on as well. Using this function I am able to achieve this about 90% of the time, however there are still seemingly random instances the child movie clips (head, body, ect.) turning back to the wrong frame for split seconds. The effect of this is I will randomly see the character's head blink into a different frame and back. This occurs without any apparent pattern or interval, just randomly changes.

My swf can be viewed here: http://www.wildtwilight.com/Zel2.html

for the example at hand I am tryng to make the head stay red, but as you move the character around (use the arrow keys) you will see it flicker back into the frame one.

I am at a loss to explain this, any ideas?