In my case it was the device that went bad(it was a wireless USB LAN adapter). One of the things that did help was to replace the device's USB cable. This helped, but as time went on, I found it would not work even on another machine.

My guess is the Ipod's cable maybe failing and that the external hard drive maybe failing,see the links below

http://forums.cnet.com/5208-10149_102-0.html?forumID=7&threadID=281361&messageID=2695915#2695915

http://forums.cnet.com/5208-10149_102-0.html?forumID=7&threadID=281361&messageID=2694758#2694758