Probaly update / reinstall "system-config-printer-gnome"
and the other packages involved.
You can do that with Synaptic.
Or use the "CUPS Administration" to set up the printer.
It is done with Firefox and this URL : http://localhost:631/
You may have to create a root password : sudo passwd root
When asked for user name : type root ( and password.)
.. If your ordinary "username" is not accepted.