This has been a problem since Poser 5.  When growing hair on a figure, it ends up kind of splotchy in areas.  Little bald patches in some places, a few weirdly long strands in others.  I'm not sure what the problem is, but it seems to happen at the edges of groups.

You can see it in my attempt at a down-covered dinosaur in the attached image.  At the back of the head.

I know some people have found a way around this (for example, Tiny's furred animals).  Does anyone know what the trick is?