Adobe Digital Editions 4.0 Getting Error "wurde zuletzt beim Öffnen von Fenstern unerwartet beendet. " (Was closed unexpectedly by opening a window)

Hi

I am working on iMac with OS X 10.8.5 and just installed Adobe Digital Editions 4.0

After having a few trials to install a book (*.epub) ADE crashed and now I only get there error "Adobe Digital Editions wurde zuletzt beim Öffnen von Fenstern unerwartet beendet. "

which means as much as "ADE was closed unexpectedly by opening a window". It asks me if I want to open it again, and if I choose yes, the same error message comes again.

I tried to delete ADE and reinstall it. Didn't change the problem.

I tried to start ADE by double click and pressing SHIFT, but that didn't help.

What shall I do?

Thanks for your help