ADE closes immediately after selecting an ebook

I can see our ebooks in Adobe Digital Editions.
But since a while it's not possible anymore to authorize (or deauthorize) an ebook, because ADE closes immediately after selecting the ebook. I use the latest version (4.5.12) of ADE. My Ebook is authorized at this moment, but sometimes it loses this authorization spontaneously.

Does somebody recognize this problem? What can I do? Remove and reinstall ADE?