Error! Check Activation

I had the same problem on my windows 7 desktop when I was prompted to upgrade to 4.53.

I tried following the instructions but it didn't work.

I did system restore and went back to ADE 2.0.

I went to the website and downloaded ADE 3.0.

After doing that, I was able to download the book without getting the "Error! Check Activation"

In fact, the ePub book I downloaded shows up in all three places.

Windows:

    Close all applications.

    Choose Start > Run.

    In the Open text box, type regedit and then press Enter. The Registry Editor opens.

    In the left pane of the Registry Editor, locate the following registry key: HKEY_CURRENT_USER\Software\Adobe\Adept

    Select the Adept key.

    Choose File > Export.

    In the Export Registry File dialog box, select Selected Branch under Export Range. Enter a name and location for the backup registry key, and then click Save.

    Right-click the Adept key and choose Delete.

    In the Confirm Key Delete dialog, click OK.

    Close the Registry Editor.

    Open Adobe Digital Editions and reauthorize.

Macintosh:

    quit Adobe Digital Editions.

    Navigate to /Users//Library/Application Support/Adobe/Digital Editions and drag the activation.dat file to the trash.

    If you are using 10.7, see https://helpx.adobe.com/x-productkb/global/access-hidden-user-library-files.html

    Open Adobe Digital Editions and reauthorize.