ght-click and choose edit with IDLE.
instead, open IDLE from the start menu and load your files from within
IDLE (should be in 'recent documents')
there's some problem with IDLE and using the separate subprocess that
only comes up when you right click and edit, so the developers made it
to where if you choose that option from the context menu IDLE boots
with subprocess turned off.
You can also edit the code for the 'edit with IDLE' menu item to get
around this, but this isn't recommended because some people will run
into whatever problem there is.
I personally haven't had any problems with re-enabling the subprocess.
-Luke