We currently have Outlook 2003 connected to an Exchange 5.5 server (neither
of these products can be upgraded), and our organisation has an LDAP server.

I have added the LDAP server into Outlook, and if you go to the Address book
and do a search, it returns all the values it is supposed to.

However, you change the order of the address books so that the LDAP server
is searched first, type a name (surname or forename) into the "To" box and
click check names then the LDAP server is not searched. Instead the
following error is generated: "The search request to the LDAP directory
server has timed out".

It doesn't matter what you set the time out to, it always displays this
error, and I know it works as searching the LDAP server via the address book
function works fine. It is only when going via check names that the problem
occurs.

Any pointers?