DFS Replication Health Report
So, lets say you have a few servers and you are playing with R2 and in specific 'DFS Namespaces' and 'DFS Replication'. As you may know 'DFS Replication' can be monitored through a built-in diagnostics report or through the Windows DFS Replication Management Pack for MOM.
The diagnostics report is generated through the new DFS Management snap-in by selecting the corresponding replication group for which you want to generate a report.
The servers you are using are just Windows Server 2003 with Service Pack 1 (with R2 of course!) with NO hotfixes. When trying to create a diagnostics report you might get a report that says that all server are unavailable for reporting (while they are up and running and replication is working). If you reboot the servers and try again it might report all servers with DFS replication errors (again while they are up and running and replication is working). Looking into the details of that messages it tells you the RPC hotfix is not installed.
So, if you want to be able to create a built-in diagnostics report, make sure the RPC hotfix (MS-KBQ908521) is installed