Does it happen with all the books you download? I would try with a whole bunch of books and if none of them work you have more information to provide to people who might be able to help you with your problem. If it is only with a few books you downloaded all at the same time it might just be what you downloaded that is defective. I have found defective books that wouldn't open and they gave that message about the format not being determinable. As Guido suggested, give us some titles to check. Sarah Van Oosterwijck http://home.earthlink.net/~netentity