Ok, so far all users with the problem seem to be running on an older image with Raspbian 8.0. Looks like there is a connection.
I have a report that
sudo apt-get update
sudo apt-get upgrade
sudo apt-get dist-upgrade
sudo apt-get update
sudo apt-get upgrade
and reboot worked for a user. So that seems to update a critical element. Also he still has a problem not seeing all gcode images.
If gui does not start any more run
sudo raspi-config
and set boot options to console with autologin.
PS: You might want to make a backup of /var/lib/Repetier-Server. It contains all settings and data. You can then also use the backup to upgrade the image to V14.
