I have a Windows Server 2003 network and I am trying to add a Windows 2008 Server Ent R2 as a DC to the network. I ran adprep /forestprep , adprep /domainprep and adprep /domainpprep on all of the W2k3 Domain Controls. When I tried to add AD roles to the Windows 2008 Server Ent R2 by running DCPROMO on the Windows 2008 Server I receive this error To install a domain controller into the Active Directory forest, you must first prepare the forest using adprep /forest prep. needs to be run. I then try to rerun adprep commands on the 2003 DCs I receive the error that the commands have already been run. Please tell me what I need to do to make the 2008 server a DC on this Network.