网页中的JavaScript问题，急急急~~~~~

我在网页中写了一段如下的JavaScript代码，在ie中能运行（能自动滚动），但是在火狐中运行就不能动了！<div id="demo" style="overflow:hidden;width:100%;color:#ffffff;"> 
        <table cellpadding="0" cellspacing="0" border="0"> 
            <tr>
                <td id="demo1" valign="top" align="center"> 
                    <table cellpadding="2" cellspacing="0" border="0" style="height: 152px"> 
                        <tr align="center"> 
                            <td> <asp:ImageButton ID="ImageButton2" runat="server" 
                                      Height="116px" ImageUrl="~/img/M_product/UFV-TC.jpg"
                                      Width="114px" PostBackUrl="~/white.aspx"  />
                            </td>
                            <td> <asp:ImageButton ID="ImageButton3" runat="server" Height="164px" 
                            ImageUrl="~/img/M_product/UFV-2A.jpg" Width="102px" PostBackUrl="~/UFV-2A.aspx"/>
                            </td> 
                            <td> <asp:ImageButton ID="ImageButton4" runat="server" Height="162px"
                             ImageUrl="~/img/M_product/FWK-J.jpg" Width="103px" PostBackUrl="~/FWK-J.aspx" />
                            </td> 
                            <td> <asp:ImageButton ID="ImageButton5" runat="server" Height="165px" 
                            ImageUrl="~/img/M_product/UFV-2F.jpg" Width="102px" PostBackUrl="~/UFV-2F.aspx" />
                            </td> 
                            <td><asp:ImageButton ID="ImageButton6" runat="server" Height="141px" 
                            ImageUrl="~/img/M_product/HRS.jpg" Width="150px" PostBackUrl="~/digital.aspx" />
                            </td> 
                        </tr>
                        <tr>
                            <td><p align="center"><a href="white.aspx"><font size="3" color="black">
                            <b>UFV-TC</b></font></a></p></td>
                            <td><p align="center"><a href="UFV-2A.aspx"><font size="3" color="black">
                            <b>UFV-2A</b></font></a></p></td>
                            <td><p align="center"><a href="FWK-J.aspx"><font size="3" color="black">
                            <b>FWK-J</b></font></a></p></td>
                            <td><p align="center"><a href="UFV-2F.aspx"><font size="3" color="black">
                            <b>UFV-2F</b></font></a></p></td>
                            <td><p align="center"><a href="digital.aspx"><font size="3" color="black">
                            <b>HRS</b></font></a></p></td>
                        </tr> 
                    </table> 
                </td> 
                    <td id="demo2" valign="top"></td> 
                </tr> 
        </table> 
    </div> 
                    <script type="text/javascript">
                        var speed3=25//速度数值越大速度越慢
                        demo2.innerHTML=demo1.innerHTML
                        function Marquee(){
                            if(demo2.offsetWidth-demo.scrollLeft<=0)
                               demo.scrollLeft-=demo1.offsetWidth
                            else{
                                demo.scrollLeft++
                            }
                        }
                        var MyMar=setInterval(Marquee,speed3)
                        demo.onmouseover=function() {clearInterval(MyMar)}
                        demo.onmouseout=function() {MyMar=setInterval(Marquee,speed3)}
                    </script>