I have been trying to install Exchange 5.5 on a test domain.  Every time I do it I get Microsoft Active Directory - Exchange Extension error ID no c007054b.
I always have a win2000 DNS machine then another win2000 running exchange 5.5 sp4, I have tried tons of different hardware and changing the LDAP port.  My routene is install dns server, update, create user give schema admin, enterprise admin, server operator, and domain admin just in case, install ADC off of 2000 CD. Install Mail machine, update, join domain, give user local admin, install admin pack, install exch 5.5, install exch sp4, install ADC off of CD.  go back to DNS setup ADC.  Every time I get the same error when I click a username in users and computers, and I dont get the extra tabs.    

Exchange 5.5 doesn't give you the extra tabs, you manage it through system manager.