As promised, I tried Vuescan to see if it would correct my problem, but it did not detect the scanner either. I spent some time researching Code 19 issues and found that they are not uncommon but are usually related to CD/DVD drives. Repairing these problems can be simple (rolling back the registry using System Restore), somewhat risky (editing the registry, provided the problem line(s) are understood), or painful (reinstalling Windows). I started with System Restore and found that I had to go back to a point before the initial install of the hacked scanner driver
to erase the Code 19 issue in the registry. I reinstalled the driver using the same process as I had originally used, and the scanner once again works normally. Of course, all the other app installs and Windows updates I had done after the System Restore point had to be repeated for my new build. Why did Code 19 happen? Not a clue, but it was not because I installed the scanner driver incorrectly. It was probably related to one of my app installs that I did shortly after the driver install. The one that I suspect was the only one that I chose not to reinstall again.
Thanks for enabling the use of Nikon scanners in Win 7! I hope my experience may help someone in the future that encounters the same problem.