Like every other service in Windows 2000, the behavior of Exchange is constrained by the access rights of the service accounts under which it runs. If you attempt to run Exchange or any of its associated services from an account that doesn't have sufficient permissions to do so, you'll get errors, the most prominent of which usually takes this form:
You do not have the permissions required to complete the operation. Microsoft Exchange Director ID no: DS_E_INSUFFICIENT_ACCESS_RIGHTS
Sometimes this error also comes up if you are using an account that has view-only rights for the object in question, and you are trying to make a change. One example of this is the MTA Queue -- you can't view the queue unless you're using a full Exchange admin account.
Many people are confused by this error, since it sometimes comes up when the user is in the Administrator account. One important fact needs to be kept in mind: the Exchange Service Account and the Administrator account do not automatically encompass each other. Unless you have explicitly granted the Administrators group a role in Exchange as Exchange administrators, certain changes may not work.
Another reason this error occurs is when a restore of the Active Directory store has taken place, and AD doesn't match the organization or site name it has been restored into. Or -- and this is rare, but it does happen -- the administrative account has been deleted before control of exchange has been transferred to another account.
If Exchange itself will not even start, then you should make sure that the service is in fact running with the proper user account. Right-click on My Computer and select Manage, and then open Services under Services and Applications. Check the Log On tab to make sure the proper account is being used (usually it runs as the Local System account).
By and large, the account that runs Exchange should be left alone, and you should rely on it exclusively to run Exchange. If you need to change it, though, that can be done, but that is something to be explored in detail in the future.
Serdar Yegulalp is the editor of the Windows 2000 Power Users Newsletter. Check out his Windows 2000 blog for his latest advice and musings on the world of Windows network administrators -- please share your thoughts as well!