Licensing for this product has stopped working (148:3) Adode Pro 9/WIndows 7

I have the original CD for when I bought Adobe Acrobat 7.0 Professional. Somewhere along the way, I updated to 9.0, but do not remember when or how. I just recently started seeing this message, and now, along with the message, the program shuts down upon clicking OK in the dialog box.

I would think that the best way to approach this might be to uninstall and then reinstall the program. However, I am not sure whether to start with my CD (version 7.0) and then upgrade from the website? Or, is there some better way.