403.1 Forbidden: Execute Access Forbidden

Hi,
I’m doing a simple email html /php contact form and i keep getting this error:
HTTP Error 403

403.1 Forbidden: Execute Access Forbidden

This error can be caused if you try to execute a CGI, ISAPI, or other executable program from a directory that does not allow programs to be executed.

Please contact the Web server’s administrator if the problem persists

Any idea why?