I believe this is fixed in Ubuntu 13.04 even if you are using GNOME according to the linked GNOME bug. I personally haven't seen this error in a long time.
** Changed in: gnome-control-center (Ubuntu) Status: Triaged => Fix Released -- You received this bug notification because you are a member of Ubuntu Desktop Bugs, which is subscribed to gnome-control-center in Ubuntu. https://bugs.launchpad.net/bugs/871985 Title: The printing panel shouldn't display errors about firewalld not running To manage notifications about this bug go to: https://bugs.launchpad.net/elementaryos/+bug/871985/+subscriptions -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs