We have made a couple of HP printers available to our students via iPrint (2x HP 5200dtn, 1x HP 6015x). About 95% of these students use OS X 10.5 :Leopard". We have discovered that when they attempt to print anything, the iPrint authentication box fails to appear. The only fix is to reinstall the iPrint client again. Once we do this, they can submit a print job, but then they have to go through this again the next time they want to print something.

Anyone have any idea what is going on and how to fix it? We are using the current iPrint client for Macs.