Edit Distribution List in Public Folder

We have recently installed Exchange Server 2000 and transfered our Outlook Address book to a public folder on our server. We can access it from all stations, add and delete contacts. We can no longer edit or add a distribution list. We get an error message that says the list has reached its maximum size or is too large. When we try to add a new Distribution List we get an error that says we failed to connect ot the server because we do not have a valid user name or password on th Microsoft LDAPconfiguation page. What are we missing here???