Creating an Excel download

In my app I have a function to create an  excel download from the database. I do this using a controller, a helper and a model

Here is my controller, Excel.php

PHP Code:

   public function export_to_excel()
    {
        $this->load->helper('excel/excel_helper');
        $export = create_excel_export();

        $filename = $export['filename'];
        $headers = $export['headers'];
        $data = $export['data'];
        header("Content-disposition: attachment; filename=".$filename." ".date("Y-m-d").".xls");
        header("Content-Type: application/vnd.ms-excel");

        print "$headers\n$data";

} 


Here is my helper, excel_helper.php

PHP Code:

   function create_excel_export()
    {
        $ci = & get_instance();
        $ci->load->model(users_model");
        $users = $ci->users_model->find_users();

        $headers = array("Employee Name", "Employee Email", "Department");

        $title = "";
        $data = "";
        $filename = 'Users';
        foreach($headers as $value) {
                $title .= $value . "\t";
        }
        $headers = trim($title). "\n";

        if (!empty($users)){
            foreach ($users as $row){
                $line = '';
                $employee_name = $row['full_name'];
                $email = $row['email'];
                $dept_name = $row['dept_name'];

                $line .= $employee_name . "\t";
                $line .= $email . "\t";
                $line .= $dept_name . "\t";

                $data .= trim($line). "\n";
            }
        }

        $export = array(
            'filename' => $filename,
            'headers' => $headers,
            'data' => $data
        );

        return $export;
    } 


Here is my model, Users_model.php

PHP Code:

   public function find_users(){
    
        $str = "SELECT * FROM users";

        $query = $this->db->query($str);
        $result = $query->result();

        $users = array();
        foreach ($result as $r){

            $user = array(
                'full_name'     => $r->full_name,
                'email'         => $r->email,
                'dept_name'     => $r->dept_name
                    );

                $users[] = $user;
          }

        }

        return $users;

    } 


While running this does cause an excel file to be downloaded as expected - the browser console report an error - 'Failed to load resource: Frame load interrupted'

I have modified my controller by adding this but it makes no difference

Code:

header("Pragma: public");
header("Expires: 0");
header("Cache-Control: must-revalidate, post-check=0, pre-check=0");
header("Cache-Control: private",false);
header("Content-type: application/x-unknown");
header("Content-Disposition: attachment; filename='theFilename.ext'");
header("Content-Transfer-Encoding: binary");
header("Content-Length: 200000");

Has anyone ever seen anything like this? I am using Safari on Mac OSX