Overview:
When using the Exchange Granular Restore option, backups complete with status code 1 (Partial Success). The message "ERR - Unable to initialize nbfsd" occurs in the Activity Monitor Job Details.


Master Server Log Files:
Activity Monitor (Detailed Status)
11/12/2008 13:01:35 - Error bpbrm(pid=6388) from client exchange: ERR - Unable to initialize nbfsd.    
11/12/2008 13:01:36 - begin writing
11/12/2008 13:01:50 - Error bpbrm(pid=6388) from client exchange: ERR - Error encountered while attempting to get additional files for Microsoft Information Store:\
11/12/2008 13:01:52 - Error bpbrm(pid=6388) from client exchange: ERR - Exchange granular restore from this image may not work.
11/12/2008 13:01:53 - Error bpbrm(pid=6388) from client exchange: ERR - Error encountered while attempting to get additional files for Microsoft Information Store:\
11/12/2008 13:01:56 - Error bpbrm(pid=6388) from client exchange: ERR - Exchange granular restore from this image may not work.

Resolution
This issue only occurs on Windows Media servers.  The error is caused by a conflict with the "Server for NFS" service on the Windows media server housing the Disk Storage Unit.  Stop the "Server for NFS" service to allow backups to complete:
> net stop nfssvc

This service can be disabled or switched to manual to prevent the service from restarting after a reboot.  Its necessary to manually start the "Portmap" service if the "Server for NFS" service is not enabled, as per Chapter 2 of the "6.5.3 Documentation Updates":
> net start portmap