Exclude password protected events and posts from the WordPress loop. Adapted from Stackoverflow: http://stackoverflow.com/questions/7538959/how-to-exclude-password-protected-posts-in-wordpress-loop

ee_password_post_filter.php

<?php 
//* Please do NOT include the opening php tag, except of course if you're starting with a blank file

// Create a new filtering function that will add our where clause to the query
function ee_password_post_filter( $where = '' ) {
    // Make sure this only applies to loops / feeds on the frontend
    if (!is_single() && !is_admin()) {
        // exclude password protected
        $where .= " AND post_password = ''";
    }
    return $where;
}
add_filter( 'posts_where', 'ee_password_post_filter' );