Why does Python not stop when it's supposed to?

[Mensanator]

So, I'm playing around with Python (running 2.6 and
3.1 versions of IDLE). After I shut everything down
and close the windows, I notice the Task Manager's
activity light is still glowing.

In looking at the Process window I see this:

Image...    User Name  CPU Memory(... Description
pythonw.exe mensanator  00      224 K pythonw.exe
pythonw.exe mensanator  00      216 K pythonw.exe
pythonw.exe mensanator  00      220 K pythonw.exe
pythonw.exe mensanator  00      220 K pythonw.exe
pythonw.exe mensanator  00      408 K pythonw.exe
pythonw.exe mensanator  00      180 K pythonw.exe
pythonw.exe mensanator  50   66,156 K pythonw.exe
pythonw.exe mensanator  00      600 K pythonw.exe
pythonw.exe mensanator  00      228 K pythonw.exe
pythonw.exe mensanator  00      208 K pythonw.exe
pythonw.exe mensanator  00      224 K pythonw.exe
pythonw.exe mensanator  00      224 K pythonw.exe
pythonw.exe mensanator  00      192 K pythonw.exe
pythonw.exe mensanator  00      224 K pythonw.exe
pythonw.exe mensanator  00      180 K pythonw.exe
pythonw.exe mensanator  00    8,672 K pythonw.exe

I can't seem to reproduce this. Opening IDLE
causes two copies to appear. When RUN, a third
appears for a few moments and drops back to two.

Doing a RESTART SHELL also launches another copy
which also goes away momentarily.

So, with a 2.6 and a 3.1 IDLE running simultaneously,
there could be 6 copies at once.

And they eventually all go away when the windows
are closed.

How is it I end up with 16 copies, one of them still
running after all the windows are closed? I had to
manually do an [end process] on all of them.

If I was doing something wrong, i sure would like
to know what it is.