Hi KOOSHAREM2
Version 1.7.2 is the answer to many problems with ADE 2.0.
ADE2.0 regularly seems to have problems with Sony and Nook devices (and some others too?); and with XP.
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