Download book from library

After several years of downloading books from library to ADE on my desktop (Windows 7), now when I do a download ADE opens on my screen but no book appears.

Just a white blank ADE screen.  When the system was working I would then drag the book into my Nook reader. I have tried ADE 4.5.3 and 2.0  I have also unauthorizing and authorizing.  Help would be appreciated.     ....................  Alex