function setStartPage() {
    var b = document.body;
    var ua = navigator.userAgent;
    var ie = ua.indexOf("MSIE");
    var iever = parseInt(ua.substring(ie+5, ie+6, ie+7));
    var os = ua.indexOf("Windows");
    if(ie > 0 && iever >= 5 && os > 0 && !window.opera){
        var homepage = "http://www.livedoor.com";
        var jumpto = "http://mail.livedoor.com/";
        b.style.behavior = "url('#default#homepage')";
        var is_home =
        b.isHomePage(homepage) || b.isHomePage(homepage + "/");
        if(is_home)
            alert("livedoor はすでにスタートページに設定されています。");
        else
            b.setHomePage(homepage + "/");
        is_home =
        b.isHomePage(homepage) || b.isHomePage(homepage + "/");
        if(is_home) {
            document.location.replace(jumpto);
        } else {
            document.location.replace(homepage);
        }
    }
    else {
        document.location.href="http://helpguide.livedoor.com/help/help/guide/grp189";
    }
}