Is the back up showing as failed by the Maxtor Backup program?
Are there any errors in the backup log?
To all users: If your data is stored ONLY on an external hard drive, then it is NOT a backup. A BACKUP is having the data stored in TWO or MORE locations. If it is only in ONE location, you don't have a backup at all. If the data is important to you, then have it stored in multiple locations to prevent data loss.
