Symptom
When you disconnect iPod's FireWire cable, an alert box appears with one of these messages:
Mac OS X 10.1
"The storage device that you just removed was not properly put away before being removed from this computer. Data on the device may have been damaged or lost. In the future, please put away the device (Choose its icon and Eject it or Drag it to trash) before removing the device."
Mac OS 9
"A FireWire disk has stopped responding. The problem must be corrected to prevent damaging the disk's contents. Please check all FireWire connections. If you added, removed, or turned a FireWire device on or off, try undoing what you did."
Solution
You should always put away iPod's hard disk icon before disconnecting the FireWire cable. Follow these steps.
Mac OS 91. Reconnect the FireWire cable to iPod. The alert box is dismissed.
2. Put away the iPod hard disk icon by dragging it to the Trash, or click its icon and choose Put Away from the file menu or Eject from the Special menu. You can also use the keyboard shortcuts by pressing the Command-Y keys or Command-E keys. In iTunes you can select iPod in the playlist and click iTunes' eject button.
Mac OS X 10.11. Click OK to dismiss the alert.
2. Reconnect the FireWire cable to iPod.
3. Put away the iPod hard disk icon by dragging it to the Trash, or click its icon and choose Eject from the File menu. You can also use the keyboard shortcut by pressing the Command-E keys. In iTunes you can select iPod in the playlist and click iTunes' eject button.