The steps I took were by the book (Building Office 2007 Solutions in C# 2005 specifically):
- verified user service account permissions. In my case the same SPConfigUser is used at all levels of the process. Please don't judge me :)
- Log into server hosting the MOSS instance as Farm Administrator
- Open SharePoint Central Administrator
- Perform backup Click continue to Backup Options. Select the path, \serverName\SharePointBackups\ProdBk
- Click Ok
The error appears to relate to permissions of the actual backup files being created:
Object PROD_productName_SSP_WEB_APP failed in event OnBackup. For more information, see the error log located in the backup directory. SqlException: Cannot open backup device '\serverName\SharePointBackups\ProdBk\spbr0000\00000014.bak'. Operating system error 5(Access is denied.). BACKUP DATABASE is terminating abnormally.