ADE might have not installed properly. Uninstall and re-install ADE 2.0.
Once installed and authorized, try to open your migrated ebooks and check.
You can get the installers from here. http://www.adobe.com/in/products/digital-editions/download.html
[Moved the discussion to Adobe Digital Editions forum]
If uninstalling and reinstalling ADE2.0 does not work, try uninstalling and installing the more reliable 1.7.2.
Version 1.7.2, it is a little difficult to find, available on Adobe site for Windows and for Mac.
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