I've worked around this by mapping a network drive and automatically reconnecting that at logon, but without that the Win XP machine won't remember the password.
Question: how do I just disable this, so the printer is shared with everyone on the network automatically without requiring them to log in to the machine over the network?
I've unchecked "Users require a password to use this computer" but all that does is automatically log in a certain account on the machine itself, a password still seems to be required to access network resources.