The Exchange Services will be using the administrator to logon to. Add a username on the DC to be used as a service logon, Make it a member of administrators and make sure the "Log on as a service" right is granted to the user. Synchronise your Domain. Then set each exchange service to use that account and password to logon to. In Exchange make that account the Service Account, Stop the exchange services, then start them in the correct order.
Check the service database for any other services using the administrator as a logon and change these to the new account and do the same at every server if needed (There may also be NT \ 2k workstations using the account You just do not know what previous staff may have done for work-arounds).
Having done all this and then double checked everything and no errors have occurred you can now change the administrators password.
Chris
This note for anyone new to Administration,
Do not use the Administrator to start services because you will have to do this everytime you change the admin password (which you should do periodically) Always add a Service logon account.
