Reboot and shutdown sometimes work sometimes don't

[Andrew Robinson]

I am getting unreliable results with the Xfce shutdown and reboot
options. Sometimes it works, and other times I just go back to xdm
instead. There is nothing in Xorg.0.log that gives me any hints to why
it isn't working. It is asking for my password, and it is accepting in
and logging me out, it is just the shutdown/reboot that is flaky.

Where can I look for more information?

Thanks,
Andrew