I upgraded to Adobe Digital Editions 2.0 from 1.7 which I use to borrow ebooks from the library. I transfer the ebooks from my computer to my Kobo ereader. Everthing was working just fine with version 1.7. Since upgrading to version 2.0 I can no longer open ebooks that I have transfered to my Kobo ereader.
I checked and Adobe Digital Edition verion 2.0 and it indicates that both my computer and Kobo reader are authorized.