You didn't mention which Windows you are using. Some users of local server software have experienced Thread Stack issues.
If your server is running on Windows, you could be getting a 500 Internal Server Error due to the fact that the ThreadStackSize is much too small. Simply append this code to the bottom of your httpd.conf file:
Code
<IfModule mpm_winnt_module>
ThreadStackSize 8388608
</IfModule>
Then restart your Apache server.