What causes the message "System (.TSX) file missing or Incorrect. Re-install the I/O catalog" to be displayed when open a PL7 Pro project?

One possible cause of this message is that the version of PL7 Pro used to write the program was higher than the version of the software being used to open the project.
This legacy software has not be qualified to run on Windows 7 64 bits.  It is compatible on Windows XP and Windows 7 32bit. It is necessary to install SP5 for windows 7 32 bit compatibility.