User ID 61 - Thank you for all of your efforts.  

I finally fixed it.  I always thought that uninstalling a program would delete all of the files in that program.  Not so in this case.  I checked after uninstalling and I couldn't tell if anything was deleted; all the files still seemed to be there.  Does Windows just hide the program from the user without deleting anything?  

I had to go in to the program directory and delete everything by hand, except for the data files.  Then I downloaded a fresh copy of the program and the prep file and it is now working.  

I suspect some files got corrupted last year when I had to replace my computer.