Gnome dies just before login screen F18

[Kevin]

I been having Gnome fail at the login screen intermittently since I
reinstalled a few weeks ago.  I read that `setenforce 0` should fix
the problem and it did for about a week, but this time I'm really
stuck.  `getenforce` returns Permissive and the problem persists. In
the attached paste from /var/log/messages I tried google for
"gnome-shell.desktop respawning too quickly" and most of the solutions
involve graphics cards I don't have.
Also, the error I see on the screen is the gnome sad face.

thanks in advance for any ideas

3.8.5-201.fc18.x86_64

http://pastebin.com/hUsewVjz


Kevin
DON'T PANIC