I have two networked machines running10.6.4 with an Epson R380 printer connected to one of the machines. I can print with that machine, and when I turn on Printer Sharing, my other machine recognizes the printer, but when I try to print, the job shows up in the queue with the message "On Hold - Authentication Required." I have removed and reinstalled the drivers on both the machines, and am running driver version 8.27 on both machines. My System Preferences on the main machine are set up to allow All Users to print. Everything worked fine prior to upgrading to Snow Leopard. Any ideas?
Do you use Keychain to manage permissions? You might try locking and unlocking your keychain. I don't really understand keychain well but I believe I have resolved the same message by entering my password in keychain. Hope that helps.