c# webbrowser控件自动提交表单，执行invokeMember("submit")没有反应

Question

我编写了一个自动登录的程序，一直能用。但今天突然不能用了，是不是那个网页的代码改了，设置了不能自动登录的功能，请高手帮我看看。
【登录程序代码】
        private void webBrowserTab0_DocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e)
        {
            switch (sStep1)
            {
                case "登录":
                    {
                        // 密码输入框
                        HtmlElement elePwd1 = MyWebTool.FindEleCollec(webBrowser1.Document, "input", "name", "pass");                        if (elePwd1 != null)
                        {
                            elePwd1.SetAttribute("value", sPwd);
                        }
                        //HtmlElement elePwd2 = MyWebTool.FindEleCollec(webBrowser1.Document, "form", "name", "gofrm");
                        //if (elePwd2 != null)
                        //{
                        //    elePwd2.InvokeMember("submit");
                        //}
                        //else
                        //{
                        //    // 登录失败
                        //    b1 = true;
                        //    GoNextUser();
                        //    return;
                        //}
                        webBrowser1.Document.Forms["gofrm"].InvokeMember("submit");
                        sStep1 = "登录结束";
                        break;
....................
.................... 
【网页代码】
...............................
<script language="javascript">
var navi_clicked = '';
function headernew(navi)
{
if (navi_clicked == '') navi_clicked = navi; if (navi_clicked == navi) {
if ($('secondline').getStyle('display')=='none')
$('secondline').setStyle('display', 'block');
else
$('secondline').setStyle('display', 'none');
} else {
if ($('secondline').getStyle('display')=='none')
$('secondline').setStyle('display', 'block');
}
navi_clicked = navi;

$$('#secondline ul').each(function(elt) {
if (elt.getStyle('display')=='block') elt.setStyle('display', 'none');
});

$(navi).setStyle('display', 'block');
}
</script>
<div id="main_w">
<div id="content" class="dl">
<form method="post" name="gofrm" action="http://nieve.tuitui8.com/login/info" onSubmit="return user_go();"> <input type="password" name="pass" class="input_mm" />
<!--<input type="text" class="input_yzm" maxlength="9"/>-->
<div class="loginerror" style="width:150px;"></div>
<div class="x_name">nieve</div>
<div class="zhmm"><a href="/getpwd">找回密码</a></div>
<div class="yzm_pic" style="top:200px; left:150px; width:80px; height:28px; background-color:#FFFFCE;"></div>
<div class="butt_qr" style="top:215px;"><input type="image" src="http://static.tuitui8.com/2.02/images/butt_qr.gif" onMouseOver="this.src='http://static.tuitui8.com/2.02/images/butt_qr-2.gif'" onMouseOut="this.src='http://static.tuitui8.com/2.02/images/butt_qr.gif'" /></div>
<div class="x_fanhui">&gt;&gt;<a href="http://nieve.tuitui8.com/info">返回</a></div> <div class="txt_wldh">每天可参加武林大会。<br />报名时间为下午13:00--24:00</div>
<div class="butt_pic"></div>
</form>
</div>
</div>
<div id="footer_w">
<div id="footer">© 2009 推推网 <a href="http://www.tuitui8.com">tuitui8.com</a> | <a href="http://bbs.tuitui8.com">推推论坛</a></div></div><div id="pageMask"></div>
<script language="javascript" type="text/javascript" src="http://static.tuitui8.com/2.02/js/ga.js"></script>
<script type="text/javascript">
//var gaJsHost = (("https:" == document.location.protocol) ? "https://ssl." : "http://www.");
//document.write(unescape("%3Cscript src='" + gaJsHost + "google-analytics.com/ga.js' type='text/javascript'%3E%3C/script%3E"));
function tuituiGoogleAnalyze() {
try {
var pageTracker = _gat._getTracker("UA-8621367-1");
pageTracker._trackPageview();
} catch(err) {}
}
if (window.addEventListener) {
window.addEventListener('load', tuituiGoogleAnalyze, false); 
} else if (window.attachEvent) { 
window.attachEvent('onload', tuituiGoogleAnalyze);
}
</script></body>
</html>和红色的script代码有关系吗？