Este error que es?

[MartinAcevedo]

Quizas esto te sirva
7. Unix/Windows: I have installed PHP, but when try to access a PHP script file via my browser, I get a server 500 error.

Something went wrong when the server tried to run PHP. To get to see a sensible error message, from the command line, change to the directory containing the PHP executable (php.exe on Windows) and run php -i. If PHP has any problems running, then a suitable error message will be displayed which will give you a clue as to what needs to be done next. If you get a screen full of html codes (the output of the phpinfo() function) then PHP is working, and your problem may be related to your server configuration which you should double check.

de http://www.php.net/manual/es/faq.installation.php

Saludos Martin

Martin Acevedo