I've had quite a number of issues with docking and undocking my JP 6910p on Windows XP, and later on Windows 7.
On Windows 7, I've found that, when it won't recognize my sound or display, I can OFTEN (not always) execute the following procedure to clear things up:
1 - lock the laptop by holding the Windows key and pressing L
2 - switch users by holding alt and pressing W
The magic here is in the switch users - it must cause the laptop to re-detect, as it then USUALLY (again, not always) figures out where to route its display and sound.