Microsoft System Center Configuration Manager 2007 backups may fail if other VSS-aware backup software is scheduled to run concurrently. In this scenario, the Smsbkup.log will show entries similar to the following:
Deleting E:\SMSbackup\SiteServer\SMSServer\inboxes\auth\statesys.box\incoming, FAILED, Win32 Error = 145 Deleting E:\SMSBackup\SiteServer\SMSServer\inboxes\auth\ddm.box, FAILED, Win32 Error = 145 Deleting E:\SCCMBackup\Backup, FAILED, Win32 Error = 145 Failed to delete the contents of the backup folder. Error Code = 0x0 SMS_SITE_BACKUP Error: Deleting the existing files in the backup location failed... SMS_SITE_BACKUP SMS site backup failed. Please see previous errors. SMS_SITE_BACKUP SMS site backup service is stopping. SMS_SITE_BACKUP
These errors can occur if the Volume Shadow Copy Service (VSS) provider is in use by another process. Configuration Manager Backup expects to have exclusive access to these resources when performing a backup.
To prevent these errors, configure Configuration Manager Backup to start at a time outside the window for other backup jobs on the server. The schedule for this can be found in the Configuration Manager Console under Site Management -> Site Code -> Site Settings -> Site Maintenance -> Tasks -> Backup ConfigMgr Site Server.
For all the details and the latest version of this document please see the following new Knowledge Base article:
KB2387913 - System Center Configuration Manager 2007 backups fail with Win32 Error = 145
J.C. Hornbeck | System Center Knowledge Engineer
It's not just VSS-aware conflicts that can make this issue manifest, I know that the Software Inventory agent can cause exactly the same error in the backup log if it is scanning a folder that VSS is trying to backup.