I'm trying to add a server 2008 r2 server to an existing 2003 domain (upgraded to 2003 functionality). I've followed the steps from microsoft which are clarified by this post:
2003 DC AD upgrade to 2008 on second server migration plan
While running adprep /forestprep I lost my connection and wasn't able to resume or remote control that session, so I couldn't see the end result of the command.

Rerunning adprep /forestprep indicates that the process has already been completed successfully. After finishing the rest of the steps (/domainprep ... and /gpprep, etc), the 2008 server won't join. The error message is the same "you need to run forestprep first"

So the situation I'm in is that I can't rerun /forestprep, but my Registry key still reads schemaVer=30. Should I have staged forest upgrades? Any ideas how to get my schema ver to 44 at this point?