For anyone just skimming this thread (which really did turn out to be very informative), the bottom line is:

Gimbal lock is very common in 3d programs, not a CL "bug", but in Poser 5 you can use the Direct Manipulation tool to get around it.

(My personal thanks to stewer. I knew about gimbal lock, I owned Poser 5 -- and I had completely missed the value of the Direct Manipulation tool.)