[dnanian]

It sounds to me like you're using SuperDuper! to back up over a network (since you can't really log into a computer as "guest" directly). If you're storing the backup on a drive inside an image, the permission setting for that drive doesn't really matter, since the image itself with have permissions ON (unchecked).

It's critical to use Permissions in general when trying to make a backup. The reason why is simple: every file and folder on the system has ownership and permission information. Checking the box (turning ownership off) makes the system ignore that information, which also makes it impossible to save and restore properly.