BACKUP PROBLEMS ON SBS 2003

[supportnet2be]

Hello, since some days , my backup has stopped !!!
here is the error i have

5/15/2006 11:00 PM
-------------------------------
Date: 5/15/2006
Time: 11:00 PM
User: SYSTEM
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Backup Runner started.
Launching NTBackup: ntbackup.exe backup "@C:\Program Files\Microsoft Windows Small Business Server\Backup\Small Business Backup Script.bks" /d "SBS Backup created on 5/15/2006 at 11:00 PM" /v:yes /r:no /rs:no /hcff /m normal /j "Small Business Server Backup Job" /l:s /f "G:\Backup SET\Backup Files\Small Business Server Backup (01).bkf" /UM
NTBACKUP LOG FILE: C:\Documents and Settings\SBS Backup User\Local Settings\Application Data\Microsoft\Windows NT\NTBackup\data\backup09.log
=====================<BEGIN NTBACKUP LOG FILE>=====================
Backup Status
Operation: Backup
Active backup destination: File
Media name: "Small Business Server Backup (01).bkf created 5/15/2006 at 11:00 PM"

Volume shadow copy creation: Attempt 1.
Timeout before function completed

Error returned while creating the volume shadow copy:0xffffffff.

Error returned while creating the volume shadow copy:ffffffff
Aborting Backup.

----------------------

The operation did not successfully complete.

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=======================<END NTBACKUP LOG FILE>=====================
NTBackup finished the backup with errors.

For more information about failed backups, see the article on troubleshooting your backup at the following Web page:

http://go.microsoft.com/fwlink/?LinkId=18414

Backup ended at Monday, May 15, 2006 11:05 PM
Backup Runner finished.


i tried many steps and it is still not working...