Mac crashes when ADE tries to open an ebook

I was able to get things to work again by throwing away ADE 4.0 (in the applications folder) re-naming the Digital Editions folder, downloading and installing ADE 3.0 and then importing the books from the renamed folder.  New downloads from the library seem to work now, and no more crashes.  I have successfully put everything back on the Nook and have also reported this to Apple.

I have tried all the reinstalling, moving and renaming the folder and re-adding the library books and this still happens.  Is it a Yosemite issue or an ADE issue?  Library books worked just fine a few weeks ago, now it seems none of them do.  Sometimes it downloads them as 0 of 0 pages, and sometimes a normal looking amount, but either way it crashes just when trying to open the file to read, or even when trying to move the file to the Nook.  The library folks seem to think it's not an issue with their files. I have been able to work around this by getting the Kindle editions which bypass ADE all together.  Is this going to be the solution, just to stop using it?

I am having the same problem on my macbook. It is making me crazy. It's any book at all...I check it out from the library, and then when I try to open it in ADE, it crashes, over and over again.

Aaargh

ADE crash in opening a specific book or with any book?