Charlie/Richie,
The problem was staring me in the face all along

. Referring to Richie's screenshot above, the Task: Create Val/Spec files is checked but no folder is specified below it where the files should be created - so the process fails and no files are created. If you click the folder browse icon to the right of that input field or type a folder name, e.g.
c:\trkmast, then the Task will work and no error message will occur.
If you don't need those files (i.e. you don't use the DOS Val4 or Spec160 software), just uncheck that Task.
I'll fix the software so you can't have the folder location empty if the Task is checked.
Does this solve the problem?
Ted