When I updated Kubuntu on my mother-in-law’s pc (yep, GNU/Linux is great for mothers-in-law — it’s hard for them to break something, and if they do it can be resolved remotely.) from version 10.04 LTS Lucid Lynx to 12.04 LTS Precise Pangolin, there were three issues upon reboot. First, KDE wouldn’t show the KDM login screen. Second, Skype could not be installed/updated. And third, the pc would not poweroff when KDE was told to do so. Here’s how I got around these.
KDE login screen (KDM)
Instead of showing the KDE/KDM login screen, a pop-up was shown with the text
Could not open the theme /usr/share/kde4/app/kdm/themes/ethais
(or similar, it was in German).
The solution is to log in to the console (as user or root) and start KDE using the command
I did this as root, if it doesn’t work for you, try
$ sudo startx
Once in KDE, you can select another KDM theme in the standard way, through Start (button) -> Computer (tab) -> System Settings (button) -> System Administration (section) -> Login Screen (button) -> Theme (tab).
Trying to install Skype gave a long list of dependencies containing 32-bit libraries (on a 64-bit system) and in the end a dependency conflict. Typing
$ aptitude search skype
showed the label “c”, which I presume stands for conflict. This was resolved by typing
$ sudo aptitude purge skype $ sudo aptitude autoclean
(though I’m not sure the latter command contributed anything). The “c” should now be gone and you can surf to the Skype website and download the Ubuntu 32 or 64 version (even though it says it’s for 10.04). Download the .deb file, double click on it and Skype should be installed (for the 64-bit version it took some minutes for the progress bar to move from 0% to 1%, but after that it was quickly done).
The issue was that when KDE was told to switch off the PC, it would halt all processes, but not poweroff. After finding out that typing “sudo poweroff” at the commandline did have the desired effect, this was easily fixed by editing the file /etc/kde4/kdm/kdmrc. In the section [shutdown], replace the line
and Bob’s your uncle.