The only thing I can think of is that you're not selecting the whole figure when you drag them. Like you're only selecting a chest or something, or the feet are parented to the floor. Wild guesses and probably not the reason.
Yeh it could be IK. Are you manually posing or applying a one-click pose? If the later then maybe the pose applies IK to all the limbs. It's not an animated pose is it? I've been out of Poser and DS for so long I don't remember much.