Can't get book from Adobe Digital Edition to Nook ereader

I've started downloading books from my public library, which uses Adobe Digital Editions (I had to download it to my laptop) and once downloaded, from there I was able to transfer the book to my Nook.  I managed to do this for two books, but now it won't transfer. 

The book is in the Adobe Digital Editions library and it looks 'normal' when I transfer it to my Nook folder/bookshelf (drag and drop), but now I get an error message that there's no permission to copy (I've tried it with three different books now).  Plus, I keep getting a Nook popup window to choose a program.  And, the book is showing in my Nook's library but when I try to open it, it tells me the program is not supported.  I don't know what's gone wrong since it had worked fine this past week.