I tried these instructions but it did not work....It would not let me delete the Adept key.
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.
Do you try to remove the key as admin?