When I try to copy a book downloaded from the library to the digital reader to my nook, I get an error message that say not authorized to copy. How do I fix this? it use to work on my old computer.

I have a Kobo, and I am having the same issues.  Never had this problem before now.  Its been a few months since I borrowed from the library.  Error message "CE_COPY_NOT_ALLOWED no permission to copy this  book.  I have a PC, Adobe Digital Editions 4.0 installed.   I have downloaded ebooks from my online library, of which the purpose is to load onto my KOBO, but I get this message.   I tried 5 different books, all do the same.  And of course I have permission to copy this  book.