I upgraded from 10.xxx to 12.04.1 LTS using the upgrade feature within Ubuntu. System upgraded but after a reboot, the graphical interface comes up. When I try logging in using a user account that pre-existed on the system, the graphical interface screen disappears, screen goes blank and then reverts to the graphical interface prompting for a password. I have loads of data and installed programs under the particular user account. PLEASE HELP....
Step one would be to try non-graphical login (press
If you can login, then you need to find out why your graphical interface doesn't work. My suggestion would be to create a new user (see for instace http://www.howtogeek.com/howto/ubuntu/add-a-user-on-ubuntu-server/ ) and log in with that. It might be some script you ran on your old installation.