The only thing I can find (others will be more helpful, maybe): http://staffcentral.brighton.ac.uk/intradoc-cgi/idc_cgi_isapi.dll?IdcService=GET_FILE&dID=4094
Either he rightly uses a LDAP (a remote directory/address book), but it isn't available somehow (then he should contact his LDAP-provider or system manager for support and check his settings) or somehow Outlook only thinks it should use LDAP while it shouldn't, because he only has a local Address Book and isn't part of a LAN. That should be in the settings also. Outlook can be tightly integrated with Exchange Server and the newer the version, the more integrated it seems to be.
I don't have Outlook 2003, so I can't check Outlook Help nor the Tools>Options.
For more information on Outlook and LDAP: http://www.google.com/search?&q=outlook+ldap+site%3Asupport.microsoft.com
Hope this helps.
From a friend: When trying to create addresses to add into a mail merge on Outlook 2003 (new version for him), he are receiving the following message:
LDAP directory is not available (52). He uses WinXP Pro. He is in Tools/Envelope/Address when this happens.
Ann in PA