JS倒计时结束卡住或提早提交的问题

我现在用一个页上用js设定了一个10分钟的倒计时器，页面上没有提交按钮，设定了倒计时为0的时候自动提交，但是现在经常出现两种情况：
   1、计时到0就卡住没反应，停在当前页，也不提交，用户还可以在文本框里面填数据，查过后台数据库却发现实际已经提交了。
   2、计时还未到0时就会自动提交，据反应有2分的也有7分多的。
   此页里另外还有一个禁回车提交的js，所有相关代码如下：
   <%
    response.setCharacterEncoding("gb2312");
//清除缓存，防止页面后退
response.setHeader("Pragma","no-cache");
    response.setHeader("Cache-Control","no-store");
    response.setDateHeader("Expires", 0); String user = "";
String mode = request.getParameter("mode");

if(session.getAttribute("euser") == null)
{
    out.println("<script language = javascript>alert('请先登录系统！');window.location.href='enter.jsp';</script>");
}
else
{
    user = (String)session.getAttribute("euser");
byte b[] = user.getBytes("ISO-8859-1");
user = new String(b);
}
%>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>考试页面</title>
<style type="text/css">

</style>

<script language="javascript" type="text/javascript">
var h,m,s,hstr,mstr,sstr,timestr;
var etime = 10 * 60;   //倒计时的总秒数为10分钟。
function timer()
{
    //h = Math.floor(etime / 3600);    //时
    m = Math.floor(etime / 60) % 60; //分
    s = Math.floor(etime % 60);      //秒

    //h < 0 ? h = 0 : h = h;
    m < 0 ? m = 0 : m = m;
    s < 0 ? s = 0 : s = s;

    //h.toString().length < 2 ? hstr = "0" + h.toString() : hstr = h; //1显示01
    m.toString().length < 2 ? mstr = "0" + m.toString() : mstr = m; //1显示01
    s.toString().length < 2 ? sstr = "0" + s.toString() : sstr = s; //1显示01

    //timestr = hstr + ":" + mstr + ":" + sstr;
timestr = mstr + ":" + sstr;

    txt.value = timestr;

    etime = etime - 1;
}
</script>
<style type="text/css">
    .float
    {
        position: fixed;
        right:220px;
        top:30px;
        width:50px;
        height:20px;
        background-color: Silver;
    }
    .long
    {
        height: 30px;
    }
</style>
<script language="javascript">
   //防止回车误提交
   //document.getElementsByName("myForm").onsubmit = function(e){
   function loadf(){
    document.form1.onkeydown = function(e){
       var evt = e || window.event;
   var ecd = evt.which || evt.keyCode;
   //return ecd == 13 ?false : true;
   if(ecd == 13){
       evt.keyCode = 0;
       return false;}
}
   }
</script>
</head><body onload="window.setInterval('timer()',1000);loadf();">
    <div id="floatDiv" class="float">
        <input type="button" id="txt" name="txt" value="" width="15" height="10" src="../img/bg_button.jpg"/>
    </div>
    <div class="long"></div>

<script type="text/javascript">
    var userAgent = navigator.userAgent.toLowerCase();
    var browser = {
        msie: /msie/.test( userAgent ) && !/opera/.test( userAgent ),
        version: (userAgent.match( /.+(?:rv|it|ra|ie)[\/: ]([\d.]+)/ ) || [0,'0'])[1]
    };    var div = document.getElementById('floatDiv');
    if (browser.msie && browser.version < 8) {
        div.style.position = 'absolute';
        var offsetTop = document.getElementById('floatDiv').offsetTop;
        window.onscroll = function() {
            var top = document.documentElement.scrollTop + offsetTop;
            document.getElementById('floatDiv').style.top = top;
        };
    }
</script>
<form id="form1" name="form1" method="post" action="dealTest.jsp">
<script language="javascript">
   setTimeout("form1.submit();",600000);
</script>

    这两种情况平均每10个人就出现1-3个，麻烦大家帮忙看下啊，很急的问题，多谢了啊！

解决方案 »

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<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
    response.setCharacterEncoding("gb2312");
//清除缓存，防止页面后退
response.setHeader("Pragma","no-cache");
    response.setHeader("Cache-Control","no-store");
    response.setDateHeader("Expires", 0); String user = "";
String mode = request.getParameter("mode"); if(session.getAttribute("euser") == null)
{
    out.println(" <script language = javascript>alert('请先登录系统！');window.location.href='enter.jsp'; </script>");
}
else
{
    user = (String)session.getAttribute("euser");
byte b[] = user.getBytes("ISO-8859-1");
user = new String(b);
}
%>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>考试页面 </title>
<style type="text/css">

</style>

<script language="javascript" type="text/javascript">
var h,m,s,hstr,mstr,sstr,timestr;
var etime = 10;  //倒计时的总秒数为10分钟。
function timer() {
    //h = Math.floor(etime / 3600);    //时
    //m = Math.floor(etime / 60) % 60; //分
    s = Math.floor(etime % 60);      //秒

    //h < 0 ? h = 0 : h = h;
    //m < 0 ? m = 0 : m = m;
    s < 0 ? s = 0 : s = s;

    //h.toString().length < 2 ? hstr = "0" + h.toString() : hstr = h; //1显示01
   //m.toString().length < 2 ? mstr = "0" + m.toString() : mstr = m; //1显示01
    s.toString().length < 2 ? sstr = "0" + s.toString() : sstr = s; //1显示01

    //timestr = hstr + ":" + mstr + ":" + sstr;
//timestr = mstr + ":" + sstr;
timestr =  sstr;

    txt.value = timestr;

    etime = etime - 1;
    if (etime ==0) {
     checkSubmit();
    }
}
</script>
<style type="text/css">
  .float
  {
      position: fixed;
      right:220px;
      top:30px;
      width:50px;
      height:20px;
      background-color: Silver;
  }
  .long
  {
      height: 30px;
  }
</style>
<script language="javascript">
  //防止回车误提交
  //document.getElementsByName("myForm").onsubmit = function(e){
  function loadf(){
    document.form1.onkeydown = function(e){
      var evt = e || window.event;
      var ecd = evt.which || evt.keyCode;
      //return ecd == 13 ?false : true;
      if(ecd == 13){
       evt.keyCode = 0;
       return false;}
  }
  }
</script>
</head>
<body onload="window.setInterval('timer()',1000);loadf();">
<div id="floatDiv" class="float">
    <input type="button" id="txt" name="txt" value="" width="15" height="10" src="../img/bg_button.jpg"/>
</div>
<div class="long"></div>
<script type="text/javascript">
    var userAgent = navigator.userAgent.toLowerCase();
    var browser = {
        msie: /msie/.test( userAgent ) && !/opera/.test( userAgent ),
        version: (userAgent.match( /.+(?:rv|it|ra|ie)[\/: ]([\d.]+)/ ) || [0,'0'])[1]
    };     var div = document.getElementById('floatDiv');
    if (browser.msie && browser.version < 8) {
        div.style.position = 'absolute';
        var offsetTop = document.getElementById('floatDiv').offsetTop;
        window.onscroll = function() {
            var top = document.documentElement.scrollTop + offsetTop;
            document.getElementById('floatDiv').style.top = top;
        };
    }
</script>
<script language="javascript">
  function checkSubmit() {
      if(confirm('确认要提交吗？')) {
form1.submit();
     }
   return false;
  }
</script>
<form id="form1" name="form1" method="post" action="dealTest.jsp">
你可以这样：
function event_timer(rt) {   rt传一个时间
   if (rt == 0){
      提交！
   }else{
       setTimeout("event_timer('"+rt+"')",1000);
    }
}