I have the answer... It took me nearly 8 hours of working on this removing hardware, software, etc. The odd thing was the reader could be seen and could be authenticated. So you would think everything was working O.K. but I too kept getting the IO error. The absolute last thing I tried was to use a different USB cable. It immediately worked... Bad cable. I hope this works for you too.
I have the same problem with my bebook, also ioError.
Previously it worked fine.
However, I have no problem transfering a free ePub book from my PC directly to the bebook (outside of ADE).
So there is no problem with the cable.