(gnome-power-manager:30469): GnomeUI-WARNING **: While connecting to session manager:
Authentication Rejected, reason : None of the authentication protocols specified are supported and host-based authentication failed.
[gpm_debug_init] gpm-debug.c:217 (15:06:17):     Verbose debugging enabled
[main] gpm-main.c:205 (15:06:17):        GNOME Gestionnaire d'énergie 2.18.3
*** WARNING ***
[main] gpm-main.c:222 (15:06:17):        Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken.

** (gnome-power-manager:30469): WARNING **: This program cannot start until you start the dbus session service.

This is usually started automatically in X or gnome startup when you start a new session.