Comment 3 for bug 301705

By removing the user from lpadmin it prompts for authentication on some programs only. For example in Adobe reader it prompts but on Gnome's programs like Gedit it does not. It's on this bug:
https://bugs.launchpad.net/ubuntu/+source/cups/+bug/283811
For adding or removing printers it works only with "gksudo system-config-printer", else it'll ask for root's password.

From the other bug:
Since Intrepid, cups or (something else) keep adding :
AuthInfoRequired username,password
In my /etc/cups/printers.conf

I tried every method I found for not changing the file, but even if the file doesn't change there is the error message. The only solution is to restart the cups service after any printing. Is there any way to tell cups to restart after completing each job? Or even something with cron to check if the specific line changed in the file?

I need some working solution because I have to prepare some PCs for students. I haven't tried it with active directory if it works. The only ways I can think is to give specific root permissions on restarting the cups service from students.