It turns out that Comodo Antivirus auto-sandboxes any program that it doesn’t recognize, and this included python in the C:\Users\$user\AppData\Programs directory.
This also affects Cygwin and MSYS2 (but not MSYS). If you are thinking about using Comodo, disable the Auto-Containment feature. Alternately, you may try to add the folder locations to the white-list, but this didn’t work for me. Have a nice day, Ryan Sent from Mail for Windows 10 -- https://mail.python.org/mailman/listinfo/python-list
