Question: I did do-release-upgrade on Ubuntu 11.10.
Now, I have Ubuntu 12.04, and I can login as a normal user, but not as root. On 11.10, I could login as root without problem.
I checked on the console, where root login works fine, and I did sudo passwd to reset the root password just in case, and I can still login on the console, but not on gnome...
Why ? Where's the problem ?