SBS 2011 Backups are failing with Volume Shadow Copy Service operation failed with error 0x800423f3.
Sharepoint is up to date and PSConfig has been run and completes successfully.
Backups are configured to run on a daily basis and have recently started failing with the above error code.
A restart of the machine allows the backup to complete successfully the first time its run but then the failures start again.
After the last failure I ran VSSADMIN List Writers and its show the majority of them to be:
State:  Failed
Last error: Timed out
Any help with this matter would be greatly appreciated