[NAME], You cannot disable VSS during backups starting from Windows 2008(if I remember it right). This is as designed by Microsoft. Usually a reboot fixes any VSS related errors unless there is a corruption in your registry. 
Hi, how to backup Networker 9.1.1.4 without VSS service enabled? Is it mandatory to enable it on the client server Please help  Rajeesh
VSS is mandatory for networker 9.1.1.4 client