When installing SBS 2011 in migration mode it replicates Active Directory during the install. If it fails the SBS 2011 installation won’t complete. When looking at the File Replication Service in the Event Viewer, and you have NtFrs errors preventing replication, it won’t finish. Change the registry entry: HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesNtFrsParametersBackup/RestoreProcess at StartupBurFlags to D4. Then go to command prompt and stop the ntfrs service “net stop ntfrs”, when it stops, restart it, “net start ntfrs”

Check the File Replication Service event logs and see if the NtFrs event logs are Information now instead of Error.

http://support.microsoft.com/kb/840674

If you want to replicate ntfrs to another server use “D4”, if you want to replicated from another server use “D2” in the registry.