I've had the same problem. Network-admin began to crash at the startup after I've added an host. Removing manually the relative line in /etc/host made network-admin to start again. Then I've tried to repeat the experiment: adding an host (using network-admin or editing manually the file) makes network-admin to crash at startup. Hope it helps.
-- [network-admin] Crash when starting from menu. https://launchpad.net/bugs/67936 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs