cause: pick pocket ui auto fires whenever a stealth character moves up against another character... even if you don't actually take anything!
result: game stops tracking all items that character has in inventory i.e, zero weight now and can't get it back unless you pick pocket again
cause: save the game standing near the hole
result: game code moves your main character to the floor under on load i.e, the game thinks you are underground and therefore can't move
work around: Jump, teleport or fly to a new location will fix the error