Windows is not passing command line arguments to Python programs executed from the shell

I think I solved this. For some reason there is a SECOND place in the registry (besides that shown by the file associations stored in HKEY_CLASSES_ROOT\Python.File\shell\open\command):

[HKEY_CLASSES_ROOT\Applications\python.exe\shell\open\command]@="\"C:\\Python25\\python.exe\" \"%1\" %*"

This seems to be the controlling setting on my system. The registry setting above adds the "%*" to pass all arguments to python.exe (it was missing in my registry for some reason).

My setting was under yet another registry key, HKEY_CLASSES_ROOT\py_auto_file. The other keys mentioned also existed, but Windows was using this one for some reason.

For Python 3.3 on Windows 7, my setting was under another registry key; the key I changed to make the arguments get passed was

HKEY_USERS\S-1-5-21-3922133726-554333396-2662258059-1000_Classes\py_auto_file\shell\open\command

It was "C:\Python\Python33\python.exe" "%1". I only appended %* to it. The key's value is now "C:\Python\Python33\python.exe" "%1" %*.

I had several (at least five) other keys with the value "C:\Python\Python33\python.exe" "%1", but this is the one I changed that made it work.