When you misconfigure any of your DNS IP, Gateway or NIC cards, you will face the issue "Failed to retrieve the pre-configuration file".
The IP address that you assigned for the SafeSquid proxy is blocked because of the firewall, you will face the issue a "Bad archive mirror". This is typically an error with the server failing to connect to the Internet.
Note: If you face any error while installing SafeSquid Appliance Builder (SAB-ISO), you will get debugging logs information by pressing ALT+F4. To return to the previous screen press ALT+F1.