Problem closing lightbox when calling AJAX

I'm having problems when on this site link session access PROJETO and click on RELEASES . While I do not click on any title that loads via AJAX the contents of the post, the LIGHTBOX closes, but when I click on the title and ajax loads the content I can not close it anymore. What could be the problem?

My AJAX:

// Classe para posts AJAX
jQuery.noConflict();
    jQuery(document).ready(function($){
        $.ajaxSetup({cache:false});
        $("a.ajax").click(function(){
            var post_url = $(this).attr("href");
            var post_id = $(this).attr("rel");
            $("#tabs").html('<div class="loading">loading...</div>');
        $("#tabs").load(post_url);
        return false;
        });
    });