Cant promote 2003 server to a DC in 2003/2000 mixed domain
I cant promote a vanilla installation of 2003 server into a single AD domain. The server is fully patched. I get the following error.
The Active Directory Installation wizard cannot continue because the forest is not prepared for installing Server 2003. Use AdPrep to prepare both forest and domain. The version of Active Directory Schema of the source forest is not compatable with the version of Active Directory on this computer.
This worries me as I already have 2 DC's in this domain that I am trying to get another dc into. I am running Exchange 2003 in this domain also. I am afraid that AdPrep will brick my current AD. I know that AdPrep has been run in this domain when I built it. Why does it need to be run again? The other 2 DC's are fully patched as well. Thanks in advance for your support.