I have software version 45.2.22 / 4.5.2.58, and I have the problem with the "ERROR OPENING BOOK, This book has been returned." message sporadically. Some books work, some don't. Most recently there was a book I erased and reloaded several times with no success, then I tried checking out an additional book and reloading both of them. Now the first one opens but the new one does not.