This can be a firewall issue (or sometimes even an anitvirus issue).
Try with firewall temporarily turned off.
There are some Vista specific suggestions at http://helpx.adobe.com/digital-editions/kb/installing-digital-editions-20-windows.html (see the top of this forum contents page).
If that doesn't help, it may be worth trying the older ADE to see if that helps.
There are lots of bugs in ADE2.0. Try replacing ADE2.0 with the older but more reliable v1.7.2.
(You can have them both installed at once if you like.)
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
I'll try your solutions today or tommorrow. I have the old adobe digital installed and it does the same thing as the 2.0 verison. So hopefully it is my firewall thats making the error appear.
I'm having this same problem, along with everyone else on this forum!
I've tried everything suggested in all the threads I can find and nothing works.
I've disabled firewalls, I've uninstalled anti-virus, I've tried both versions of Digital Editions, I've removed the old registry keys, and I cannot get it to connect to the authorization server. I have another computer at this location which can connect, so it's not a router/ISP problem and it's not the server itself being down.
At this point I cannot borrow any books from my library because it requries the use of Adobe Digital Editions.
I don't know what else I can possibly try. Is there some small file or registry key buried somewhere that might be causing this issue?!
I doubt this will help people with this problem, but given what you have tried it is the only thing I can think of.
Try installing the Sony Reader program and using it to open the .acsm files you download from the library and get the Adobe ADRM file. https://ebookstore.sony.com/download/
That is designed to work in conjuction with Sony eReader devices, but also works standalone. It may be that for some odd reason it can register where neither version of ADE can. If you do use it, after you have downloaded a DRM .epub file (via the .acsm key file), you will need to do the transfer of the .epub file to any non-Sony device using a file manager (Windows Explorer, Mac Finder, ...).