<div id="demo" style="overflow:hidden;height:180;width:210" align="center">
<div id="demo1" align="center">
<table width="210" border="0" align="center" cellpadding="0" cellspacing="0">
<tr>
<td height="5"></td>
</tr>
<tr>
<td height="35"><img src="images/sub1.gif" width="210" height="35" /></td>
</tr>
<tr>
<td height="5"></td>
</tr>
<tr>
<td height="35"><img src="images/sub2.gif" width="210" height="35" /></td>
</tr>
<tr>
<td height="5"></td>
</tr>
<tr>
<td height="35"><img src="images/sub3.gif" width="210" height="35" /></td>
</tr>
<tr>
<td height="5"></td>
</tr>
<tr>
<td height="35"><img src="images/sub4.gif" width="210" height="35" /></td>
</tr>
<tr>
<td height="5"></td>
</tr>
<tr>
<td height="35"><img src="images/sub5.gif" width="210" height="35" /></td>
</tr>
</table>
</div>
<div id="demo2" align="center"></div>
</div>
<script>
var speed=30
demo2.innerHTML=demo1.innerHTML
function Marquee()
{
if(demo2.offsetTop-demo.scrollTop<=0)
demo.scrollTop-=demo1.offsetHeight
else
{
demo.scrollTop++
}
}
var MyMar
function beginmarquee()
{
MyMar=setInterval(Marquee,speed)
}
function endmarquee()
{
clearInterval(MyMar)
}
//var MyMar=setInterval(Marquee,speed)
//demo.onmouseover=function() {clearInterval(MyMar)}
//demo.onmouseout=function() {MyMar=setInterval(Marquee,speed)}
</script>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> 下显示正常，Firefox下也可以。但只要头部用的是
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
就无效了，只有这句demo2.innerHTML=demo1.innerHTML被执行，表格撑成两倍大
------解决方案--------------------
那就是你的代码写的不规范导致的
1、第一行<div id="demo" style="overflow:hidden;height:180;width:210" align="center">改为:<div id="demo" style="overflow:hidden;height:180px;width:210px" align="center">
2、demo,demo1,demo2获取不到ID，你用documentgetElementById分别获取demo,demo1,demo2
你再试下