This evening I encountered a weird problem when booting up Ubuntu 10.04. I simply had a black screen with a small error window saying:

There is a problem with the configuration server.
(/usr/lib/gconf2-4/gconf-sanity-check-2 exited with status 256)

Considering that I hadn’t knowingly changed anything last time I used the computer this seemed a little odd.

The following also appeared in /var/log/syslog:

Oct 13 22:05:34 hostname gnome-session[450]: WARNING: Error retrieving configuration key ‘/apps/gnome-session/options/auto_save_session’: Failed to contact configuration server; some possible causes are that you need to enable TCP/IP networking for ORBit, or you have stale NFS locks due to a system crash. See http://projects.gnome.org/gconf/ for information. (Details –  1: Could not send message to GConf daemon: Process /usr/lib/libgconf2-4/gconfd-2 received signal 6)

Fortunately the fix turned out to be easy; it’s simply a permission problem with /tmp. To fix it simply run:

sudo chmod 1777 /tmp