F18: GDM sometimes won't load desktop

[Anthony]

Howdy All,

For some reason, there are times when I log into the system and it
simply won't load the desktop. The GDM shows me the login prompt, I
select my username, enter my password, and it says 'Logged In' with the
little green checkmark next to it. But it just sits there. It doesn't
load the desktop and the only way to get to the desktop is to restart
the system and log in again.

This happens with no rhyme or reason. Just 'sometimes' and always at
system boot.

I'm running F18, fully patched, with XFCE as the DE.

Has anyone experienced this? How do I fix it?

Thanks!
Anthony