I had similar problems few times. What I did wrong:

• in scenes where were more then 1 figure I set collide against wrong figure (often happend when you have "Figure1 and Figure2"

• default/dynamic group was not corerrect. Add all verts to default group.

• Poser 5 did not react for checking/unchecking "ignore hands/feet" collision. P5 always ignored them.

Maybe you did one of above misstakes?