When I plug in my Ipod Video to my Apple Macbook, nothing happens. It doesn't appear in Itunes or in 'My Computer' and so I cannot safely disconnect it because it doesn't come up anywhere. When it's plugged in, the Ipod flashes and says 'Do not disconnect!'. It doesn't update and freezes when I unplug it. This hasn't ever happened before, any suggestions? Thank yoooooou .