How can I fix the "Error getting License" message?

I often download e-books from my library.  With EVERY epub book (.acsm) I get the message "Error getting License. License Server Communication Problem: E_ADEPT_REQUEST_EXPIRED".   I cannot read any of these books.

I have tried deautorizing my computer, and reauthorizing it. I have confirmed my Adobe ID,  I have confirmed that the date, time, and time zone on my computer are all correct.

So what is the problem?