Repeated authorisation required?

Earlier this year, after many years of untroubled use, I could not open a book. It said I was not authorised, even though I have been for years. I used the erase authorisation function, re-authorised myself, and it worked fine. Now today it refused to work again and it would not erase my authorisation like it did last time. I uninstalled ADE and reinstalled, but it was still the same. After a search online I found a solution involving editing the registry and it now works.

This can't be right? Something should be done. I am competent at registry editing, but I don't like doing it. A less experienced user would be stuck.