How can I fix my frozen creative zen? It's tricky?

It's a creative zen vision:m mp3 player.
I recently left it with someone who repeatedly left it plugged into the computer while the PC was being switched off and overnight while the PC was off.
Now whenever I unplug it the screen displays the "docked" message (it still thinks it's connected to the computer).
The player will not respond to any buttons being pressed in this state.
I have tried formatting the device and removing and replacing the firmware but now, when i connect it to my PC it cannot transfer data (music or video files) very well at all(It will start transferring but, after transferring about one song the PC will print a message saying "semaphore timeout period has expired!" and will then not transfer until I press the "OK" button, in which case it repeats itself and sends one song (after a while) then gives the same error message).
Also, when I disconnect the player, it still thinks it is docked and forces me to reset it every time I disconnect it from the PC.
Once reset though it works normally (with a severe lack of music after the formatting!).
I've tried everything I can think of, can you please help?