When you start up your system, the netwok manager systray applet doesn't appear. You go to a terminal and try to launch nm-applet manually, but you get the following error:

** (nm-applet:788): WARNING **: <WARNING>        nma_dbus_init (): nma_dbus_init() could not acquire its service.  dbus_bus_acquire_service() says: 'Connection ":1.8" is not allowed to own the service "org.freedesktop.NetworkManagerInfo" due to security policies in the configuration file'

Well, there are a couple of things that could be going on here. You could edit the configuration files for netwrk manager in the /etc/dbus-1/system.d path to allow default permissions instead of deny, however this is definitely not the most secure method.

A better alternative is to add any users you wish to use Network Manager into the netdev group.

After making either cange, you must either reboot your system, or reload the dbus daemon.