Half-Broken filetype association in XP

[Gerry]

Under XP, until yesterday, I typed a.py in a dos box and a.py ran
fine; typed a.xls and opened an excel window; typed a.doc and opened a
word Document.

Type, all of those fail - if typed in a DOS window.  They all work --
if clicked in an explorer window.

The registry looks fine (to me, fwtw):

 assoc from a Dos prompt says:

.py=Python.File
.pyc=Python.CompiledFile
.pyo=Python.CompiledFile
.pys=pysFile
.pyw=Python.NoConFile

and ftype says

Python.CompiledFile="C:\Python25\python.exe" "%1" %*
Python.File="C:\Python25\python.exe" "%1" %*
Python.NoConFile="C:\Python25\pythonw.exe" "%1" %*

which all look pretty good to me.

Typing \python25\python a.py succeeds, too.

I may be the victim of a corporate software overnight push.  (And so I
have no way to back it out.)

Can anyone help me out?