Unity not showing after 11.04 upgrade. Cannot log out to switch to classic?

I have upgraded an old desktop that I use as HTPC from 10.10 to 11.04. It has an old 256MB Nvidia card. After the upgrade ubuntu will boot but all that shows is the wallpaper, no unity, windows, nothing. The problem is I had the box configured to auto login and so now I cannot log out to switch to Classic mode (which I know works because it works on the liveCD!).

How can I log out when I cannot see anything? Terminal will not display. Is there some key combination at boot that will allow me to force it to classic mode (unlikely). Can I boot into a liveCD, mount the hard drive and change some config file to turn off auto login?

Any help much appreciated! I don't want to format the drive and start over!

Solution 1:

Try typing CTRL ALT F1 and logging in.

Then type

sudo killall Xorg

this should kill the Xserver and leave you at the login screen.

When selecting your user account, click the Session drop-down at the bottom of the screen and choose Ubuntu Classic

Solution 2:

Try this:

1. Hit ctrl-alt-f1 to enter a virtual terminal and log in with your username
2. Type the command sudo nano /etc/gdm/custom.conf and enter your password again
3. In this file, change automaticloginenable=true to false
4. Hit ctrl+x, y, then enter to save and quit
5. Enter sudo reboot

You should get a login window at boot now, probably with an auto-login countdown, so make sure you catch it in time to switch your session

Solution 3:

You can force a terminal screen by holding Ctr-Alt-F1. Then edit /etc/gdm/gdm.conf (sudo gedit /etc/gdm/gdm.conf). Look about 20-30 lines down for "AutomaticeLoginEnable" and "AutomaticLogin" and comment out those lines. Once that's done save the file then you can logout using gnome-session-save --kill. Then Ctr-Alt-F8 to go back to the GUI.