I have the same problem. It is a complete new install, over an old one
(this old was completly formated except the /home).
I've tried to reinstall gnome-panel, and chmoded the gconf.xml.system (775 ?
strange rights isn't it?), reboot, but nothing changed :
after log in gnome, the message error
No more problem !
Like I said, I've installed the new ubuntu over a old installation, keeping my
/home. During the install, I've put my home partition on the /home mount point.
All my files was so owned by root.
A little sudo chown sebsheep:/ /home/sebsheep (sebsheep is my logname