I have a HP Deskjet F4180 printer attached to my server computer, which runs Debian. I have a Ubuntu 9.04/Windows XP machine that connects to it fine and can print just fine.
I have a second computer which runs Ubuntu 9.04 which used to work just fine up until a few days ago when I ran some updates before upgrading the distribution. Now, when ever any user on the system tries to print, they are prompted for a user name and password in a dialog saying "Authentication Required". Entering user names and passwords into these does not allow it to print, it remains in the queue with the status "held for authentication".
Any ideas what this can be? I can't find anything on the internet about this problem, and as I said it works fine on another Ubuntu installation and Windows installation.