I spent the morning trying to figure out what the hell was going on with iTunes and my iPod. Usually when I figure out these sorts of things if I post about what I did to solve them I get a lot of google hits from people who had the same problem. And this one was a doozy.
Affected software and hardware: iTunes for the Mac 4.6 and iPod w/ OS 2.2. These are the most recent software updates for both iTunes and the iPod.
Problem: When the iPod is plugged in iTunes would first refuse to update it, then it would go into spinning pizza wheel mode, and then it would completely hang the system, requiring a total shut down and reboot. Force quit does not work. Kill -9 does not work. If you pull the iPod out the dock while iTunes is spinning pizza at you, you can deeply injure your iPod’s disk, requiring a restore or even a reformat with Disk Utility. Don’t do that.
Other people who posted about this problem could get partially through an iPod update with iTunes, but the transfer would be incredibly slow, and eventually iTunes would go into spinning pizza and hang the machine as above.
The solution. Get this: Unplug iSight. Everyone who had this problem including me also had an iSight video camera. And apparently iSight doesn’t play well with other devices on the firewire bus — or at least iTunes doesn’t like it. Unplug the iSight, reboot, plug the iPod in, and all will be well.
(Hmmmm. I wonder if this was the issue with my external HD enclosure, too).