Have a problem with an iMac running Panther. It was an upgrade from OS 9.2.
Simply through having enough of Entourage not doing what OL2001 did, put OL2001 back on and - yep - it runs (obviously).
However, much as it seemed to resolve the Exchange server under the settings, and after initial install all seemed to work, after a reboot, it will no longer resolve the exchange server to log it into.
Terminal pings the server, and even tried setting a hosts file which makes no difference, it simply will not log in. In the OL Settings the only way it would resolve was to put the IP address is but it then reverted to the server name and voilá - won't log in.