I've got exactly the same configuration NT 4 sp5, python 1.5.2, grail 0-6 and it worked well . I had to modify the registry to call the *.py files directly from the DOS shell, as you do. Have you tried > python grail.py just an idea.... BTW, I find that grail 0.6 is still not really useable, although it is a very intersting project.