I got the notification of available update but when I hit 'update' muon says:
"this operation cannot continue since proper authorization"
but I was not asked for administrator authorization!
(My OS is Ubuntu Oneiric)
Any suggestion?

I had to open a new session in Ubuntu (Unity) to get my system updated.

Do you have a process named "polkit-kde-authentication-agent-1" running on your system?

bcooksley wrote:Do you have a process named "polkit-kde-authentication-agent-1" running on your system?

no, I have not... Shouldn't it be loaded automatically by the system at startup?

If you are using the KDE desktop, then yes it should be automatically started. The process name under a GNOME/Unity desktop session would be different. If you open Konsole, and try to run "polkit-kde-authentication-agent-1" then what message do you recieve?

Thanks bcooksley, sorry for delay...

bcooksley wrote: If you open Konsole, and try to run "polkit-kde-authentication-agent-1" then what message do you recieve?

I get:
polkit-kde-authentication-agent-1: command not found

Very unusual. You will likely need to use sudo in combination with apt-get install to install the needed package (at which point, it should start working - although you may need to logout and back in again for it to kick in).

Unfortunately I don't know the name of the needed package. I believe the syntax to search is "apt-cache search".