Download Problem

I downloaded an epub book to my windows PC from my local public library site via overdrive.  I can open the book on line but when I tried to download it so I could move it to my Nook I got an error message from Adobe Digital saying Unable to Download. Error getting license: License Server Communication Problem.  E_STREAM_ERROR.  I have used this same site and procedure on this same PC for several years and this is the first time this has happened.