When using metacity as window manager, running "xfce4-session-logout --logout" from the command line fails. The first attempt does nothing. Further attempts result in a dialog that says Failed to receive a reply from the session manager Session manager must be in idle state when requesting a shutdown I redirect the startx output to a file, and when I run the logout command I get the message "This option is not available. Please see --help for all possible usages." Not sure where that is coming from. Oddly, if I just do "xfce4-session-logout" and push the logout button, it works fine.
Similar experience for me, as detailed in http://forum.xfce.org/viewtopic.php?pid=24210#p24210
duplicate of #5379. Reopen if you still have the issue and symptoms are different.. *** This bug has been marked as a duplicate of bug 5379 ***