have same problem, started yesterday. searching archives here, it starts now and then, "no one" knows why and there are never any answers or fixes.
Personally, I think Adobe turned off one of their license servers and it's one hard-coded into the version of ADE we have. So there won't be any acknowledgement or fix - we'll have to try upgrading to see if it has any positive effect (an upgrade has been the only solution I've seen listed here in the forums and only by one user; all others never found a fix).
I have the same problem. When will Adobe address a fix for this issue?
Eureka! I have a solution to those of us who could no longer download digitized ePublications onto our somewhat dated Nooks. For the record I have a NookCOLOR,
1. Select the available ePub book that you want from the library. Confirm that is the book you want. A string message will appear with
the book title within it and will end with .acsm (which is a root file). You will also see the following message, Invalid Menu Handle.
Click it off and ignore this.
2.Go to the downloads in your browser, place your cursor over the file and right click. You will then open up a temp file and the
book that you want will be highlighted. Right click again and where it says Open With, right click again that it should open with
the Adobe Digital Edition you are using (probably 3.0 or 3.01).
3. Your Adobe Digital Edition will now open and the book will be downloaded. (You will actually see this happen as you did before).
4..Connect your Nook to your computer.
5. Click Library designation and you will see that the Nook is now on the top of all the files presented. Using your cursor as you had done many times before, move the downloaded book onto your Nook. Sign out of library and disconnect your Nook correctly.
6. Open up under My Files, Digital Editions and your downloaded book is ready for reading.
I have done this about seven or 8 times and each time the download was successful. I have not attempted this with any audio books but I assume that the results will be the same.