"The writer experienced a partial failure. Check the component level error state for more information."

Hi,

It seems my VSS is severely corrupted/damaged, somehow. When I attempt to do a backup with Windows Server of the system state, bare metal recovery, C: and part of D: drives, I get the following error:

As this includes a Hyper-V backup, the Hyper-V VSS Writer is activated. I am backing up to another partition on the physical HD of the host (VMs on another physical HDD). Error details are below:

The backup operation stopped before completing.
Detailed error: ERROR - A Volume Shadow Copy Service operation error has
occurred: (0x80042336)
The writer experienced a partial failure. Check the component level error state for more information.


Log of files successfully backed up:
C:\Windows\Logs\WindowsServerBackup\Backup-03-05-2010_00-02-05.log
 
Log of files for which backup failed:
C:\Windows\Logs\WindowsServerBackup\Backup_Error-03-05-2010_00-02-05.log

A Volume Shadow Copy Service operation failed. Please check "VSS" and "SPP" application event logs for more information.
ERROR - A Volume Shadow Copy Service operation error has
occurred: (0x80042336)
The writer experienced a partial failure. Check the component level error state for more information.

Although this is from another app (BackupAssist), they stated I should raise this issue to MS as they have no fix. I also had a similar problem with Windows Server Backup. When I do a backup of C:, partly D, bare metal and system state in Windows Server Backup, I get this error:

The VSS service is running.

What's causing this error?

Thanks