I had trouble downloading ADE -- since it was late at night I decided to not pursue it -- I went back to the Sony software to copy my new books to my Reader.
When I did that, it asked me if I wanted to authorize the Reader and warned me that I would not be able to read books on it if I didn't do it. I agreed and it authorized both the Reader and the computer that I was using.
When I looked at my account settings, I noticed that while I previously had two computers and my Reader authorized for my account, I now only had one computer and one Reader. If all of my authorized devices were removed when they switched formats, that explains why I couldn't open the books.
It's tempting to buy another book now to see if I'm right (I wished I'd only recopied one book instead of all four of the ones I had just bought) but there is no reason for me to not wait until I'm ready to buy again.
