For those getting a 1604 and 1601 error when resotring their ipods after pre jailbreaking, if you have the C dist installed, are using the correct unaltered 2.2.1 firmware and are not using cutom boot logo's this is most likely your fix, your not properly in DFU, to get into dfu hold home and power for 10 secs or until your computer plas remove hardware sound and then let go of power and hold home until your computer plays hardware connected sound, this will put your ipod into dfu, hopefully this is your fix!