Try running nm-applet --sm-disable, if you aren't already. nm-applet in gnome likes to add itself to the session as restart, so it'll get restarted automatically, and it doesn't make sure it's the only instance running.
-- Many instances of nm-applet loaded in Xfce panel https://launchpad.net/bugs/47825 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
