by Bret Miller.
Generally this means you've created a redirect loop between Apache and Moodle. For example, you might tell Apache that the website URL must be http://127.0.0.1/ and in Moodle's config.php $CFG->wwwroot might = 'http://localhost/'. This creates a loop where Apache redirects the browser to http://127.0.0.1/ then runs Moodle which redirects back to http://localhost/ causing Apache to redirect back to... endlessly.
Make sure Apache and Moodle agree on the host name.
