Host - ubuntu 11.04 desktop
VM - ubuntu 10.04 desktop
Virtualizer Oracle VirtualBox

After upgrade the VM to 12.04 LTS, on reboot only a black sreen was displayed.

Drop to root shell on restart

# startx /usr/bin/gnome-session
Faital server error:
Could not create lock file in /tmp/.tX0-lock
...
ddxSikGiveUp: Closing log

# ls -l /tmp
Code:
drwx----- 2 root root 4096 ....
# chmod 1777 /tmp
Code:
chmod: changing permisions of '/tmp': Read-only file system
Pls help. TIA

B.R.
satimis