Digital Editions E_LIC_LICENSE_SIGN_ERROR when adding a book to library

I am attempting to add a book (acsm) to my library and am getting an error E_LIC_LICENSE_SIGN_ERROR.

I have tried uninstalling (via Windows Control Panel) and re-installing, unauthorizing and reauthorizing, deleting the Windows registry key, resetting my Adobe password. I have also tried a different computer.

I have contacted support and they have advised that I should post here as there is a cleaner tool for Digital Editions and that someone from support will assist.