how to avoid an infinit loop trying to show a php start page with php + jquery

I've been working on a web page with php + smarty + jquery + html.

The problem, I need to display the diferent content of a web page using the window.location = mainPAge.php insted of $("#div-Page").show()

In other projects I make a simple switch like this:

$(document).ready(initialize);

function initialize{
       showPage("none");
}

function showPage(page){
       switch (page) {
        case "none":
            $("#mainDiv").show();
            $("#webDiv2").hide();
            $("#webDiv3").hide()
            break;
        case "opcion2":
            $("#mainDiv").hide();
            $("#webDiv2").show();
            $("#webDiv3").hide();
            break;
        case "opcion3":
            $("#mainDiv").hide();
            $("#webDiv2").hide();
            $("#webDiv3").show();
            break;
}

And it work perfectly, but now I cant use this, I need to use the pages from php directly so I use this:

$(document).ready(initialize);

function initialize{
       showPage("none");
}

function showPage(page) {
    switch (page) {
        case "none":
            window.location = "mainContent.php";
            break;
        case "opcion2":
            window.location = "secondContent.php";
            break;
    }

The problem !!! It seems that when I mix jQuery "$(document).ready(initialize)" with "window.location = 'mainContent.php'" the browser goes into an infinite loop.

I really dont know why and less how to avoid the loop, if i dont try to show mainContent.php at the begining of the page, and I asigned a button to show the mainContent.php, that way work perfectly.

But I need to display mainContent.php for automatic way to start page.

I appreciate so much your suggestions.

Regards !!!!