Problem Solved!

Not a Windows issue but a Proseries issue.  Went to the path mentioned by ckevin and there I renamed the user.config file to user.config.old and restarted ProSeries 21 application.  File recreated and application opened.

Thanks ckevin

C:\Users\gregr\AppData\Local\Intuit,_Inc.\protax21.exe_Url_5leag0hqmnnrx052avintxz33iuoxkpb\0.0.0.0\user.config

Why does the Uninstaller not remove this directory and any other directories the application creates?