Backup Traps

During a full backup some backup software look like they are backing up your directories but they are not. When you point the program to the folder it then writes a list of the files and only backs these up.
Similarly CD burning jobs in some programs work from a file list not a folder list. There is a big difference because each file added to a directory is often more valuable than one of the existing files.
Now that you know, test your "backup and burn" assumptions. Especially if you backup using a full, not an incremental backup.