How to reset Windows Vista "Complete PC Backup"
If you are trying to "Backup Up Files" or do a "Complete PC Backup" via the "Backup Status and Configuration" wizard, you may find a "Backup status" dialog box indicates that you have already done a backup and need to plug in the media, that contain this backup information to update the backup data on this media. If you do not have this media, you have to reset this "Backup status" information by pressing
Win + R and opening regedit.
Afterwards you have to navigate to
delete all keys and "sub folders" there,
except the "Default" key in "WindowsBackup". That is it!