Attached Link: http://poser.smithmicro.com/tutorials/Characters_rigging.html

That's where you're going wrong.  You'll need to rethink what you think you know about rigging when dealing with Poser. X=twist,y=side-side and z = bend in an XYZ setup. However, if a body part...let's say the foot for example... twists on the z axis naturally, you're not going to want to make your x axis a twist. So for the foot you'd want something closer to ZYX.  We actually have a helpful guide to suggested joint orders:

 

http://poser.smithmicro.com/tutorials/Characters_rigging.html