Have almost the same issue.
On both Cluster Servers Windows 2003 SP2 cannot backup System State:
Event viewer has only:
End Operation: Warnings or errors were encountered.
Consult the backup report for more details.
backup.log:
"Cluster Service Writer" has reported an error 0x800423f4. This is part of System State. The backup cannot continue.
Command "vssadmin list writer" return error:
Writer name: 'Cluster Service Writer'
Writer Id: {41e12264-35d8-479b-8e5c-9b23d1dad37e}
Writer Instance Id: {f2f99318-0cb7-4745-986d-162482a18166}
State: [8] Failed
Last error: Retryable error
Could anyone help?