jQuery document.ready strange behaviour
Page.ClientScript.RegisterStartupScript(GetType(), "Script", "ShowPopup('popup');", true);

function showPopup(p) {
    ShowFancyBoxDiv("#divMessage", 50, 300);
}

$(document).ready(function () {
    setTimeout(function () {
        ShowFancyBoxDiv("#divMessage", 50, 300);
        $("#fancybox-close").css("display", "none");
    }, 1000);
});

$(window).load( function() {
   //code
} );