I've tried the regedit hack (deleting the Adept key) after getting the Error: Check Activation message when trying to open a .acsm from the library (OverDrive), and being unable to Erase Authorization using the menu.
I exported the Adept Key (under the Device sub-registry), then deleted the key. I closed regedit, opened ADE, and it's still authorized. I then closed ADE, uninstalled it, deleted the key from the regedit again, and reinstalled ADE, and it's still authorized. When I try to unauthorize, I get the "Unable to Erase Authorization. Please try after some time." error, although I've been trying this for about 4 days now.
Help? ADE is the only option I have to download and transfer library books to my Kobo, and this is VERY frustrating.