pfSense

This happens when the IP address has changed because of the restore.

This also needs to be tested restoring a configuration that changes the host or domain, because that might trigger the DNS rebind check, too.

This is happening to me on 2.0 RC3, nanobsd, with a clean install.

Steps to reproduce:
changed interface defs via serial after initial boot (was initially LAN / WAN, I swapped them)
Defined static IP for LAN via serial
initial setup wizard worked, but when I saved the settings, webGUI breaks.

Rebooting the box seems to resolve the issue, but something weird is happening behind the scenes. I was also seeing an incorrect IP address on the LAN interface after enabling DHCP via the serial console. (The LAN interface was showing the initial address from the DHCP pool??) Again, reboot fixed that.

2.0-RC3 (i386)
built on Sun Jul 31 05:05:32 EDT 2011

Same as Braden, changed interface, swap WAN and OPT1. Change WAN from DHCP to Static, through webgui. After reboot, all the settings of the packages were set to default.

If the LAN IP address is entered in the URL: An HTTP_REFERER was detected other than what is defined in System -> Advanced (http://192.168.100.1/pkg_edit.php?xml=squidguard.xml&id=0). You can disable this check if needed in System -> Advanced -> Admin.

If the domain name is entered in the URL: Potential DNS Rebind attack detected, see http://en.wikipedia.org/wiki/DNS_rebinding. Try accessing the router by IP address instead of by hostname.