ADE 4.5.4 hangs up and won't open epub from my library

[msearly]

Recently updated from 4.5.1 to 4.5.4. Borrowed epub books from local library system (worked fine 2 weeks ago). Digital Editions hangs up (not responding) when I try to open the books, and hangs up when I try to copy to my Nook (original edition).

[msearly]

having this problem again. I uninstalled ADE and then reinstalled. Used trouble-shooting techniques given elsewhere in this forum -- deleted old files, cleared cache.  I can sometimes easily borrow a book via Overdrive from my library system and open it. But in the past 2 days I cannot get any title to work. The file appears on my computer, but ADE will not open it. Just hangs up.