I installed python using the installers from python.org -- I originally reproduced this using github actions using pyflakes's testsuite

>ver

Microsoft Windows [Version 10.0.19041.985]

>venv\Scripts\python --version
Python 3.10.0b1

C:\Users\asott\AppData\Local\Temp\y\pyflakes>venv\Scripts\python --version --version
Python 3.10.0b1 (tags/v3.10.0b1:ba42175, May  3 2021, 20:22:30) [MSC v.1928 64 bit (AMD64)]

to reproduce:

```
git clone https://github.com/pycqa/pyflakes
cd pyflakes
git checkout b02ba019e16f7c156ec63c2ea05c627a0fe86c48
```

# install tox somehow
```
C:\python310\python -m venv venv
venv\Scripts\pip install tox
```

here are the versions I have at that point:

```
>venv\Scripts\pip freeze --all
appdirs==1.4.4
colorama==0.4.4
distlib==0.3.1
filelock==3.0.12
packaging==20.9
pip==21.1.1
pluggy==0.13.1
py==1.10.0
pyparsing==2.4.7
setuptools==56.0.0
six==1.16.0
toml==0.10.2
tox==3.23.1
virtualenv==20.4.6
```

then run this a few times:

`venv\Scripts\tox -e py310`

even with `setenv = PYTHONFAULTHANDLER=1` I couldn't get a trace, though maybe that's a linux thing?

it occasionally crashes like this:

```
py310 run-test: commands[2] | flake8 pyflakes setup.py
ERROR: InvocationError for command 'C:\Users\asott\AppData\Local\Temp\y\pyflakes\.tox\py310\Scripts\flake8.EXE' pyflakes setup.py (exited with code 3221225477)
```

from some googling:

> in hex is 0xc0000005 which is the Windows code for an access violation


I don't do much development on windows so I'm passing the torch to someone who knows more :)