Comment 50 for bug 283811

>As Paul said & others as well elsewhere on the internet, some have had success with workarounds where I have not. >Could this be some combination of downloaded software that is causing this?
Well, I see it like keeping adding the said line is a symptom.
The authentication error that triggers the symptom can be slightly different for each user.

>If all my PCs are running Ubuntu 9.04 do I need Samba to share printers & files?
no, CUPS should be fine.

After applying the workaround, where you able to print once?

I suggest that:
1) You apply the said workaround:
lpadmin -p <printer_name> -o auth-info-required=none

2)In Ubuntu Gutsy or newer, select "System" -> "Administration" -> "Printing" in the main menu of your desktop. The printer setup tool system-config-printer will open.

3)Go to the troubleshooting wizard in system-config-printer. You find it by in the "Help" menu of system-config-printer. It produces a text file with a lot of useful information to attach to bug reports. Follow the instructions of the wizard. If you reach the test page step, you can either click the button to print the test page or you can print a job to the selected printer from any application or from the command line. The job will be shown in the integrated job viewer. Wait until it completes or goes into "Stopped" state. ONLY THEN AND NOT BEFORE mark the checkbox at the job, answer whether the job got printed correctly, and click "Forward". After that the file will get generated. Save it and attach it to this bug report.

[Step 3 were taken from https://wiki.ubuntu.com/DebuggingPrintingProblems#Troubleshooting%20Wizard ]