It did exist, yes.  I called Proseries and they told me to consult my IT guy.  He had me update windows, then deleted the Pronet22 folder and ran the install file as admin (rather than installing from the TY21 software.)  This seems to have done the trick, although I have now been getting a different error about a missing file.  This error does not say what file is missing.  A reboot corrected this error, but it reappeared after closing and reopening Proseries.  I will retry again today and see if the error persists.