In working through a problem with updating exchange 2003 for Daylight Saving Time following procedure http://support.microsoft.com/kb/932599to remove well known security identifiers from exchange using the Exchange Administration Delegation Wizard, I have removed the NT AUTHORITY\SYSTEM user. After removing that user and a BUILTIN\Administrators at a lower level I was able to mount the database. Is NT AUTHORITY\SYSTEM necessary and how can I add it back ( the Exchange Administration Delegation Wizard does not find the user when I try to add it back to the Organization)??? Thanks for any help.

ROFL - rule number 1, never play with default permissions unless you know precisely why they there and have a valid reason for them to be revoked. Having looked at my exchange 2003 server security settings, system is not listed at the organization level so i would say your problem lies deeper down the line, most likely where you removed the administrator object and the permissions were being propogated downwards. You need to enable Security Tab in ESM, this is done through a registry hack which can be found in the following kb264733 When adding the system object, make sure the local computer is selected in locations then simply type the name system in the user box.