Yesterday I've upgraded my Kubuntu 14.04 to 14.10 thinking it would be safe to do so right now. The upgrade proceeded as expected but somehow my user account apparently lost admin rights.
If I try to connect Wifi I get "Not authorized to control networking" That's about the same as described here: Not authorized to control networking. The solution described there doesn't help.
If I go to system settings to try to create a new user account I see immediately a message on top of the screen telling me that I can't save the settings. The same problem happens if I try to change the login screen.
Shutting down or restarting the computer in the regular way is also impossible and only throws me back to the login screen.
There's nothing disturbing in dmesg or any other relevant logfile I can think of.
I've issued the command 'id' in the terminal and this gives a normal list as far as I can tell.
I've checked the sudoers file and it looks completely normal.
In recovery mode I've tried the command
adduser myusernamehere sudo and it says my username is already in the sudo group.
I've found out the wired network connection still works.