ADE Crashes opening library book from OneClickDigital (Mac OSX 10.9.5)

I'm new to ADE.  Our local library started offering eBooks this past week via OneClickDigital.

eReader is ADE.  I loaded 4.0 on my Mac and downloaded an eBook.  ADE crashes every time I download a book or attempt to open the book.

After the crash, the book appears to be downloaded - I can even open the Mac Finder and see the pdf on my hard drive in Documents->Digital Editions.

I've tried various ways to open the book - double clicking, right-clicking the book icon and selecting read and selecting the book and using the File->Read menu.  All of them result in a crash.

Any suggestions?  I've seen recommendations to load earlier versions of ADE, but I don't know a legitimate source for that.

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