After logging into ubuntu the screen turns orange with a cursor and gnome does not load the window manager.
The system seems to be frozen but it is not.
Hitting alt-Prnt Scrn pops up the print dialog.
Hit control-alt-backspace to restart gnome. At the logon prompt look at the bottom
left of the screen and choose options: fail-safe terminal. Inside terminal Type:
sudo apt-get install gnome
if this errors out Type:
sudo dpkg --configure -a
Reboot and gnome should be working correctly.