Hi I was having the same problem using ADE 2.0.
I contacted the LiveChat support (link button did not show when using Firefox 31), which gave me this link. http://helpx.adobe.com/digital-editions/kb/error-e_act_not_ready.html
After I edited the Registry and then restarted ADE I was able to ReAuthorize my machine. Hope this works for you.
I have the same problem. Do U have an idea?