Try with firewall temporarily disabled.
There are lots of bugs in ADE2.0. Try replacing ADE2.0 with the older but more reliable v1.7.2.
Though I haven't heard of that particular thing being an ADE2.0 bug that 1.7.2 fixed.
You can have both 2.0 and 1.7.2 installed (and even running) at the same time.
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