Codeigniter is stuck in some kind of nesting loop.

It is strange, looks like infinite recursion.

Code:

<?php
class News_model extends CI_Model {

        public function __construct()
        {
                $this->load->database();
        }
}

Try this workaround:
1. Remove the line $this->load->database();
2. Autoload database using the configuration file autoload.php