1.8.2014

Yesterday I installed the recommended updates with the Muon Update Manager. Then I put my notebook into sleep.

Today I started the PC - and surprisingly it was booting instead of just waking up.

In KDE the notification came:

KDE Power Management System could not be initialized. 
The backend reported the following error: No valid Power 
Management backend plugins are available. A new installation might 
solve this problem. Please check your system configuration.

In the application launcher menu the entries for Sleep, Shut Down and Restart were missing!

I reinstalled (or just reinitialized) upower

sudo apt-get install upower

This brought back the icons in the launcher menu.