Strange Behavior of Physical Object?

This is my first time working with a Physical object, so I'm at a lost to know what to make of this. I'm working on an elevator, and when you press the floor button, the elevator car is turned physical, and moves up or down. Once you reach the floor, the script turns the Physical property of the Prim back off. Well sometimes, the prim *appears* to continue to move slowly in the previous direction of travel. However by continuing to stand on it I can see it's not actually moving, and if I click to edit it, it suddenly snaps back into position. Can anyone tell me why this is happening? :\

It's been a while since I did this, but I did a llSetPos () after I turned the phyysical off to get it to the correct position. It always finished not quite right otherwise.

Thanks for the advice, I'll give it a try.