I had this happen yesterday. After killing all NetworkManager-related processes (NetworkManager, NetworkManagerDispatcher and nm-applet), and restarted them, things were back to normal. Using "/etc/init.d/netapplet restart", "/etc/init.d/networking restart" or simply killing and restarting "nm-applet" had no effect at all.
Note that it does not always happen, most of the time everything works as normal. -- NetworkManager can't find interface on resume from suspend https://launchpad.net/bugs/45696 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs