Hmmm... one item to try is to connect your Clara HD to your computer and deauthorize it. Once this is done, take a look at the root of the exposed USB storage for a directory called ".adobe-digital-editions". Open the directory and take a look at the contents. You should see a single file called device.xml. If you see another file called activation.xml, delete it (you may have to set Windows to show hidden files to see them while Mac OSX will need to be set to allow you to see hidden directories since Unix based OS use a . at the start of a name to say it is hidden).
Safely disconnect your Clara, reconnect it and authorize it from ADE (assuming you have any authorizations left). If you then disconnect, open Settings and take a look at Accounts to make sure the email address under Adobe matches the one used for your Adobe account under ADE.
If you have exceeded your Adobe activation limit, that is going to involve contacting Adobe customer service.
|