Hmm, that's weird! Can't say I've never had hair move on me -- it has. Its been a while though. Hair is supposed to parent to the head (as long as the prop was put in the right spot in the first place). I also have the Yann hair, but I'm not having this problem. Try this: Delete the hair from your current workspace and save your scene. Open the scene back up in Poser and apply the hair again. Before you render, use the hieriarchy editor and hide everything except the figure and the hair and see if the same thing happens (this way you won't wait 20 min to render). If it works right turn everything back on and render.

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