When trying to restore your iPhone in iTunes, you may see the following message followed by an error code 1601 or 1602:
The iPhone could not be restored. An unknown error occurred.
Or when trying to restore your iPod touch in iTunes, you may see the following message:
The iPod “[username]” could not be restored. An unknown error occurred (1602)
Follow the steps listed above for Error 1604. This error may also be resolved by disabling, deactivating, or uninstalling third-party security, antivirus, and firewall software. See steps in this article for details on troubleshooting security software.
Completely remove iTunes and Apple Mobile Device support and then reinstall iTunes 7.5 or later.
Important: Information about products not manufactured by Apple is provided for information purposes only and does not constitute Apple’s recommendation or endorsement. Please contact the vendor for additional information.