Leopard: network users can’t log in, automount home directories

My network users are suddently getting the "Unable to log in the user account at this time ... The home folder of your user account is located on an AFP or SMB server" message when they try to log in to a client computer; previously they were able to log in just fine. I can test in Terminal and see that the FQDN is working and the client computer is bound to the Open Directory and shows all the users in the Users folder. In Workgroup Manager a home folder is designated for the user and WGM creates all the home files in that folder. The AFP log shows a quick login/logout of the user; the Open Directory LDAP log shows slapd40 :