E_ADEPT_REQUEST_EXPIRED could mean that a library loan has expired.
It can also happen if you get times or times-zones wrong.
There are quite a few bugs introduced in V2.0 that were not there in v1.7.2.
If you don't need the new features of V2.0, you might find an install of 1.7.2.
You can have both installed at once.
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