The thumbnail probably comes from the jpg itself. The JPG format allows for thumnail previews to be embedded in the larger file. Unless there is an thumbs.db like MGD suggested.

As for backup. I store the originals on my computer and a copy on my server. The chance that they both fail at the same time is very slim (bar a devestating fire ofcourse).

What is a friend? A single soul dwelling in two bodies. - Aristotle
-= Glass Eye Photography =- -= My Rendo Gallery =-