ADE, MacBook Air, and Nook problems

I downloaded Adobe Digital Editions and then a book (ePub format) from my local library. Both ADE and my nook are authorized to the same email address. However, when I try to open the book to ADE, I get his error message: "Error getting License. License Server Communication Problem: E_ACT_NOT_READY."

If I try to deauthorize my ADE (or erase authorization), it says: "Unable to erase authorization. Please try after some time." I waited a couple days and tried again, but I got the same response.

What should I do to be able to open the book in ADE? I have a MacBook Air.