Well, ok. Here is my work flow, and how the problem developes:

I load Sydney into the scene. From there I give myself anywhere from 150 to 300 frames to build the animation. I don't have anything else in the scene at this point, including the hair prop.

I don't do pose to pose because there is too much tweaking involved after the fact, so I just move her body around attempting to create realistic movement. Sometimes it involves bending her head and neck to achieve the look and effect I want.

Once that is completed, I load the hair. It is her strand based hair prop that comes with Poser 8. I don't make any changes in the material room at this point. I do however, select the skull cap and click on collision detection for that, her head, neck, shoulders and collar.

Her hair is in five parts, left and right bangs, left and right side, and back. I run each part separately with 'do collisions' checked.

It's about the time that the dynamic simulation reaches the point where her head is tilted either up or down, or she may be lying on her back that Poser hangs for an infinite amount of time. If I touch the mouse or disturb it in any way, I get the Windows 7 message that Poser has stopped working and needs to be closed. I sat there and let the program run for 3 hours one day only to have it stop working and have to be shut down. I restarted my computer and ran into the same problem at the same point. I have even tried to work the animation so that her head bending is gradual, but it's always the same. Seems to go out when her head gets beyond a 30 degree angle in either direction. It doesn't happen with her head side to side as much.

And Sydney isn't the only model I have had problems with. It seems that all figures with strand based hair will do the same thing.

The only time I have an issue in the hair room is if I am attempting to calculate dynamics on the hair if her head is anything but upright. I didn't do a pose or animation that didn't have her head upright for the better part of 6 months because if that. I recently attempted it again, and the same problem exists.

Is this specific enough?

If I had a nickle for ever time a woman told me to get lost, I could buy Manhattan.