Another possible solution; dump ADE2.0 and install the older 1.7.2.
There are lots of issues with 2.0 that were fine on 1.7.2.
I've never seen issues like yours resolved this way, but almost certainly worth a try.
As there is some interaction between the way the two store their data, 1.7.2 may inherit some registration etc from 2.0.
So probably worth trying the ctrl-shift-D on 1.7.2 to help clean up historic rubbish.
Version 1.7.2, it is a little difficult to find, available on Adobe site for Windows and for Mac.
http://helpx.adobe.com/digital-editions/kb/cant-install-digital-editio ns.html
The forum software is sometimes corrupting the link above. There shouldn't be a blank in 'editio ns.html'. The following redirects to the same page: http://tinyurl.com/diged172