From the Source Core Replication Tab, the Target Core hostname is displayed as 000000's instead of the hostname of the Target Core. Additionally all Replicated Agents has the status 'Deleted'.
This state can occur if the Source Core was shutdown unexpectedly in an ungraceful fashion while a replication job was performed. For more information on Graceful shutdown of the Core service, please review: How To Stop the Core Service (Kb 119400)
Windows Registry Disclaimer:
Quest does not provide support for problems that arise from improper modification of the registry. The Windows registry contains information critical to your computer and applications. Make sure you back up the registry before modifying it. For more information on the Windows Registry Editor and how to back up and restore it, refer to Microsoft Article ID 256986 “Description of the Microsoft Windows registry” at Microsoft Support.