Trouble Authorizing a computer

Try uninstalling ADE, downloading the latest version

Adobe Digital Editions | Download

then reinstalling it.  You may have to reauthorize it.

A lot of software you install and if it runs, it will continue to run, because the software is completely resident on your computer.  If the operating system changes radically, it may then fail to run, but the OS people generally try to avoid this because it Makes the User Unhappy.  Alas the restraint and care that OS people take is not present at Adobe.  They regularly mess with the backend of ADE and then it stops working in weird ways with misleading/unhelpful error messages.....or no error message at all.  See you think you install ADE on your computer, but what you install is just the front end of ADE, the pretty face that takes a request for DRM management but doesn't actually *do* anything with it...other than passing it to a backend program at Adobe. The people at Adobe regularly and without notice do things to the backend that make your frontend fail.  If, in ADE, you go to Help, About Digital Editons and look at the the version number, you will see something like 4.5.7.182628. This means that there have been nearly 200,000 versions of the current 4.5.7 ADE frontend (well, not really, but you get the idea)...which means that Adobe ADE development has been doing all kinds of changes (and changing the backend)....and the more changes that are made the more likely it is that the ADE front end you use, that was working just fine last week, no longer works.  In computer speak, Adobe development change control is a disaster.  They are playing very fast and loose and changing a lot of things all the time without telling us.  Of course, when you have the only game in town for DRM management (as ADE does), you can do anything you want, and we have to lump it. And they never tell us what changes they are making and why.  It's called an monopoly. Isn't this fun?

So if weird things happen and ADE stops working, here is the straight skinny: Try downloading and reinstalling it. Right.  And if that doesn't work (maybe Adobe has screwed things up and they are working to make it right), wait a day, download a fresh copy and try another reinstall. Rinse and repeat until ADE starts working again.  Until the next time.