In general, for Windows 2008 clients it could be that the VSS System Writer 
will be missing from the list although your message does not show it.
In this case, you should follow this recommended procedure:   
http://social.technet.microsoft.com/Forums/en-US/windowsbackup/thread/bb760434-de80-4cb6-ae9e-bd253e4b037c
Here is the short version:
  Takeown /f %windir%\winsxs\filemaps\* /a 
  icacls %windir%\winsxs\filemaps\*.* /grant "NT AUTHORITY\SYSTEM:(RX)"
  icacls %windir%\winsxs\filemaps\*.* /grant "NT Service\trustedinstaller:(F)"
  icacls %windir%\winsxs\filemaps\*.* /grant BUILTIN\Users:(RX)
  net stop cryptsvc
  net start cryptsvc

--------------------------

Otherwise i always stop the NW client service.
I have rarely noticed an orphaned nsravtar process. Kill it before you
Restart the NW client service.

Worst case, i would try a reboot.

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