What does this really mean? It comes up when you click HELP in ADE and click the "Autoriize Computer" option. I created several adobe IDs and made sure none were in use; but, they all threw off the message E_AUTH_USERID_INUSE, and then the error box suggested I try again.
I succeeded at authorizing my ADE about three weeks ago (I think it was version 1.7) and from there was able to enable my Kobo Glo to handle books from the public library. Maybe it's 2.0 that's stopping me, but I remember I got the message with 1.7 too.