How come my iPod touch's contents cannot be read on any computer?

Whenever i plug my ipod touch in to a computer (Windows and Mac) it automatically says " itunes cannot read the contents of the ipod. Go to the summary tab in ipod preferences to restore this ipods factory settings." I have already tried this on each of my computers and i recovered the setting but the same thing keeps showing up. I have even tried using different usb plugs ,usb slots and i made sure that it works on my family's different ipods. Please Help!