There was an error during the CUPS operation: 'client-error-not-authorized'.

[hal9000a]

I'm unable to change the setting of the actual printer on my system, cant even delete it
i go trough the menu : system/administration/printing
the system ask me the root password, after i enter it, i always get this message "There was an error during the CUPS operation: 'client-error-not-authorized'."

the web interface don't allow me to modify anything
always telling me that i need to give the password without asking for it

is there a way to reset everything, maybe its the easiest way ?