Fatal error when using ‘#’ character as an admin menu link title

I figured out the problem: You must specify an ID in the add_menu array if the title is not alphanumeric. So, this code worked:

function my_admin_bar_menu() {

    global $wp_admin_bar;
    if ( !is_super_admin() || !is_admin_bar_showing() )
        return;

    $wp_admin_bar->add_menu( array(
    'title' => __( '#'),
    'id' => __( 'my_menu_item'),
    'href' => admin_url('myurl.php')));

}

add_action('admin_bar_menu', 'my_admin_bar_menu');

The only change is the addition of the line containing ‘id’.