Please restart your machine and try again.
I have recently been having all kinds of problems with ADE. I have had ADE 3.0 installed for quite some time with no problems until very recently. Long story short I ended up deauthorizing ADE, and then couldn't authorize my computer again. I tried everything, uninstalling, reinstalling, rebooting, nothing worked. Finallly went into my administration account and ADE showed as authorized, but when I tried to add a library book it told me it wasn't authorized, so I deauthorized in my admin account, and reauthorized and it worked. Tried to add the book, and it transferred, then plugged in my Kobo Glo & was able to add the book to it as well. When I change from my admin account to the one I normally use, the book I just added doesn't show, & ADE doesn't show as authorized. None of it makes sense, but try running from your admin account and it may work for you as well.
None of the prior steps helped me at all. However, what I just did that worked was to delete ALL versions of ADE on my computer and reinstall version 4.0.
I had updated from v3.0 to v4.5.2 to deal with the ASCM files type but got in the same endless loop of failure to authorize or failure to connect to authentication server, both errors (falsely) suggesting I was not connect to the internet.
The registry editing, DE-authorizing/re-authorizing, shutting down windows firewall/Norton antivirus etc. just cycled me through these error messages without solving the problem.
I don't even know when v4.0 was downloaded or if it was automatic at some point, but by uninstalling v3.0 and v4.5 and selectively installing v4.0 everything worked the way it should.
I must say I found the chat people with whom you connect when you click the Help tab in ADE was worthless (actually worse than worthless since the snarkily pointed out it was free if necessary software and therefor not supported) and the Forum articles simply cycled me through useless and sometimes scary (deactivating all my PC's security features) steps without resolving the problem.
V4.0 works as it should. Now I just have to figure out how to assure it will not auto-update and put me back in server failure hell.
Hope this helps others. Good Luck out there...