adobe digital editions freezes when I try to download a book from my library

I also have trouble with downloading ebooks from library to kobo ereader.  The book appears in ADE - and I can open it there, but when I transfer it to eareder I get a message that book is protected by DRM and that I have deauthorised my reader.  I have tried everything - numerous time authorising and deauthorising - borrowing more different books - factory resetting reader - all to no avail.  Any suggestions?