Assuming you are using XGL, this is a known error. However, there is a workaround.
Your startxgl.sh file should be as follows: #!/bin/sh Xgl -fullscreen :1 -ac -br -accel glx:pbuffer -accel xv:pbuffer & sleep 4 export DISPLAY=:1 cookie="$(xauth -i nextract - :0 | cut -d ' ' -f 9)" xauth -i add :1 . "$cookie" exec gnome-session -- Missing Shutdown and Reboot buttons from gnome "power" button https://launchpad.net/bugs/93551 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
