(Not Responding)

I've been trying to download an eBook from my local library, as I have plenty of times before.  However, this time, every time I try downloading it, Adobe Digital Editions hangs and becomes non-responsive.

I've used Task Manager to force quit the application a few times, only to find multiple copies of the problematic book available in my Bookshelves.  However, these copies are just as problematic.  Trying to copy them to a device (my Nook) or reading them on Adobe Digital Editions itself also causes ADE to become non-responsive.  Looking on my Nook itself, there are no copies there. 

Any ideas?