I upgraded my packages in my Ubuntu 10.04 Lucid Lynx Beta 1 installation and it required a restart. I did not realize that there was no space left on the root partition (I have two partitions, root / and /home). I restarted and was not able to login. I got a message saying something like
The configuration defaults for GNOME power manager have not been installed correctly. Please contact your computer administrator
in the Login window. I tried logging in again, but I again got blank screen and was logged back out. Nor did the message make any sense.
I pressed Ctrl+Alt+F1 and logged in there and then tried to upgrade the packages using
sudo apt-get update sudo apt-get upgrade
There were upgrades available and installed them I saw mandb complaining about the lack of disk space. I then freed some space by deleting some files I had kept in the root directory and pressed Ctrl+Alt+Del to restart and it booted in without problems. If you face this problem and want to free some space, you can use
sudo apt-get clean
which will free the space used by package archives cache which are located at /var/cache/apt/archives and it should boot without problems.