Internet Explorer, jQuery, session lost php

问题:

I have an unsual problem. I am developing an website witch is behind a load balancer. We have 4 frontends. For some reason, in Internet explorer, session is lost. We are using database session and it is working in all other browsers. After days of debugging, i eliminate the following lines from a JS file:

$('div').each(function(){
    console.log($(this));
    if($(this).attr('role') == 'dialog') {
        $(this).addClass('callmenow_wrapper');
    }
    if($(this).attr('class') == 'ui-dialog-titlebar ui-widget-header ui-corner-all ui-helper-clearfix') {
        $(this).addClass('callmenow_title');
    }
    if($(this).attr('class') == 'ui-dialog-buttonpane ui-widget-content ui-helper-clearfix') {
        $(this).removeClass('ui-widget-content');
    }
    $('button').addClass('button-call-popup');
});

Now everything is working as expected. If i put back this lines in IE, the session will be lost. If anyone has experienced something wired like this, please advice.

Thank you.

PS: I read tons of documentations and similar problems. I've set P3P headers, etc. Nothing worked until i removed this lines.