My ipod was doing a similar thing--it would say do not disconnect when plugged into my usb, and when I opened itunes, Itunes would freeze. What I did was went to computer and found where my ipod was listed. Right clicked, clicked on format, and clicked Restore Device Defaults. That ran for literally a few seconds, and immediately afterwards, Itunes popped up and recognized my ipod. I finished wiping my ipod with itunes (restored it to factory settings so there was nothing on it), and that seemed to fix it. All my music in my itunes library was still there, so all I had to do was sync my ipod to that, and it restored all my music.