Odd as it sounds, this is exactly what is supposed to happen, sagefisher. The nail knot merely secures the braided loop and it is the 'Chinese-finger-puzzle' effect that keeps it on, and like a puzzle, it is easy to take off in the right manner.
While I most just use heavy, stiff, mono in a butt section with loop-to-loop connections, I use the braided loop for shooting heads and large game situations and the system works just fine. Dan Blanton's site, that someone else cited, describes precisely how it is best done.