The intent of this section is to collect the quite numerous frequently asked question that relate to working with Terminal, or even terminal emulators in general. If you know of a question that's missing from this page, please file a request.
Terminal tries to reduce the number of running instances by establishing a D-BUS service that handles all terminal windows. The message above tells you that Terminal wasn't able to connect to the D-BUS session message daemon and register a service. This is just a warning, you can use the terminal without the D-BUS service feature as well.
To start the D-BUS session message daemon when you login to your X session, either
modify your xinitrc file and change the line xfce4-session to
dbus-launch xfce4-session or use dbus-launch startxfce4
to start Xfce instead. If you don't use Xfce, please look at the documentation of your
desktop environment on how to enable the D-BUS session daemon.