I received the same error messages. I first had a Be Book which 'died' after only one day. I had successfully registered it. I now have another e-reader, IT Works. However, it does not work since I cannot register the reader. I entered the pasword but it came up with above-mentioned error messages. E-reader works fine with books that are free of cost. It is obviously a problem related to DRM which should be solved on Adobe's side. I have not yet found solutions for computers running with Windows.
I finally got my Elonex ereader to work by resetting the ereader to factory
default settings and then going through the authorisation process again.
BTW I created a webcase on the Adobe support page and they were the ones
that suggested I do this.
I hope it works for you. Annette.