I am having the same issue on a MacBook Pro, OS10.9.5. It worked perfectly up until today, and tonight it won't work. Of course I have homework due on Wednesday from the book that I can no longer open. I've deactivated and reactived ADE, and still nothing works. The message I'm getting is: "Error getting License. License Server Communication Problem:
What is this? It's worked fine for the past six weeks and now it doesn't work?