is this with all disks or just backups !?The problem with C13:00 (Disk is dirty) error is usually very easy to be fixed. The error is probably based on the different reflexion of the laser beam, which can be caused either by any kind of the dirt on the bottom layer OR, FREQUENTLY by a sticker or any legend made by a black marker (or any kind of dark and thick) on the UPPER side. I suggest NOT to put anything on the top side.