To identify the cause of this error, initially run a vssadmin list writers from a command (DOS) prompt on the machine after the backup has failed.
Confirm that the SPSearch4 VSS Writer is showing a status like the below:
Writer name: ‘SPSearch4 VSS Writer’Writer Id: {35500004-0201-0000-0000-0Writer Instance Id: {6d7435c2-c142-48State: [8] Failed Last error: Inconsistent shadow copyThis is the SharePoint VSS writer and although you may not have SharePoint installed / configured, Windows will need to see the associated VSS writer in a stable state before it will continue with a System Protection job.
To address the status of the writer follow the steps below:
Please also see http://social.technet.microsoft.com/Forums/en-AU/winserverfiles/thread/920bf71e-be19-49eb-9f2b-ebcf70ad8177 which gives further details regarding this error.