In my case it seems to be a network settings problem. in my /etc/network/interfaces the lo device is configured as:
auto lo after system startup the lo device is not alive. Starting gnome gives the well known white box in the left bottom corner. After sudo ifconfig lo up in the base terminal gnome starting up without any problem. -- gnome-settings-daemon crashes at login https://launchpad.net/bugs/61381 -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs