Error in VSS - Backup Exec job fails to make a backup

Server: MS Server 2003 Enterprise edition (DHCP, DNS, AD Server)
Backup software: VERITAS Backup Exec 9.1 Rev. 4691

Backup was ok for about 18 months. Last 2 days backup is failing with this error in application log:

Event Type:      Error
Event Source:      Backup Exec
Event Category:      None
Event ID:      34113
Date:            03/03/2005
Time:            02:38:16
User:            N/A
Computer:      SERVER
Description:
Backup Exec Alert: Job Failed (Server: "SERVER") (Job: "SERVER_BACKUP") Server_BACKUP -- The job failed with the following error: A failure occurred querying the Writer status.
 

 For more information, click the following link:
http://eventlookup.veritas.com/eventlookup/EventLookup.jhtml


Error in Backup exec’s log is:

Job ended: Thursday, March 03, 2005 at 12:36:34 PM
Completed status: Failed
Final error: 0xa000fed1 - A failure occurred querying the Writer status.

Final error category: Resource Errors


After checking the status of the VSS I get:

H:\>VSSADMIN LIST WRITERS
vssadmin 1.1 - Volume Shadow Copy Service administrative command-line tool
(C) Copyright 2001 Microsoft Corp.

Writer name: 'System Writer'
   Writer Id: {e8132975-6f93-4464-a53e-1050253ae220}
   Writer Instance Id: {47210fb7-e401-4d7f-b1dc-4cbfd96a01cb}
   State: [5] Waiting for completion
   Last error: No error

Writer name: 'MSDEWriter'
   Writer Id: {f8544ac1-0611-4fa5-b04b-f7ee00b03277}
   Writer Instance Id: {e08e5c27-34d8-499f-a957-ffed41b18b6c}
   State: [1] Stable
   Last error: No error

Writer name: 'Registry Writer'
   Writer Id: {afbab4a2-367d-4d15-a586-71dbb18f8485}
   Writer Instance Id: {685f766d-c088-4d6b-8ff3-6c16aab70259}
   State: [1] Stable
   Last error: No error

Writer name: 'Event Log Writer'
   Writer Id: {eee8c692-67ed-4250-8d86-390603070d00}
   Writer Instance Id: {5248a46f-9f74-4cf8-92d8-57e08e3a647a}
   State: [1] Stable
   Last error: No error

Writer name: 'COM+ REGDB Writer'
   Writer Id: {542da469-d3e1-473c-9f4f-7847f01fc64f}
   Writer Instance Id: {076fb130-1ba0-4800-80a7-959e32e06bf2}
   State: [1] Stable
   Last error: No error

Writer name: 'Dhcp Jet Writer'
   Writer Id: {be9ac81e-3619-421f-920f-4c6fea9e93ad}
   Writer Instance Id: {e587e4ed-253a-4955-9371-8d1de6dd35bf}
   State: [10] Failed
   Last error: Retryable error

Writer name: 'FRS Writer'
   Writer Id: {d76f5a28-3092-4589-ba48-2958fb88ce29}
   Writer Instance Id: {0632bd48-1eaf-4623-b94f-b07e0fb9c506}
   State: [5] Waiting for completion
   Last error: No error

Writer name: 'WMI Writer'
   Writer Id: {a6ad56c2-b509-4e6c-bb19-49d8f43532f0}
   Writer Instance Id: {d02eb37c-9453-4def-93b0-3b67babf2833}
   State: [5] Waiting for completion
   Last error: No error

Writer name: 'BITS Writer'
   Writer Id: {4969d978-be47-48b0-b100-f328f07ac1e0}
   Writer Instance Id: {a8ccdca3-614c-470b-8cde-813dbd0563be}
   State: [1] Stable
   Last error: No error

Writer name: 'NTDS'
   Writer Id: {b2014c9e-8711-4c5c-a5a9-3cf384484757}
   Writer Instance Id: {d9aa3531-3dc9-43fd-9f94-a9ea48d31ea8}
   State: [10] Failed
   Last error: Retryable error

Any suggestion where to look for solution.