登录界面弹出框有关问题

<?php//session_start();?><script language="JavaScript" type="text/javascript">function chk_login_input(form){    if(form.email.value=="")    {        alert("请输入邮箱");        form.email.focus();        return false;    }    if(form.password.value=="")    {        alert("请输入密码");        form.password.focus();        return false;    }     return true;}</script><style type="text/css"> td { border-right: 1px solid #C1DAD7; border-bottom: 1px dashed #C1DAD7; padding: 6px 6px 6px 6px; color: #4f6b72; font-family:"黑体";font-size:20px;} </style><div id="login" style="text-align:center;margin-top:80px;margin-left:150px;background-image:url(../images/login-bg.png);width:492px;height:395px;">     <form action ="login2.php" method="post" name="login" onsubmit="return chk_login_input(this)">        <p>&nbsp;</p>        <p>&nbsp;</p>        <p>&nbsp;</p>        <table style="margin:auto">            <tr>                            <td>Email:</td>                <td><input type="text" name="email" size="20"/></td>            </tr>            <tr></tr>            <tr>                    <td>密码:</td>                <td><input type="password" name="password" size="20"/> </td>            </tr>            <tr>                <td><input type="image" name="submit" src="../images/login-icon.png" onClick="document.login.submit()"></td></td>            </tr>        </table>        </form></div><?phprequire 'connect_to_database.php';$email=$_POST["email"];$password=$_POST["password"];$dt=mysql_query("select * from userinfo where email='".$email."' and password='".$password."'");if($dt == true ) //访问数据库成功{    $row = mysql_fetch_row($dt);    if($row == false)//是否从数据库里提出到了东西    {        echo '<script type="text/javascript"> alert("邮箱或密码错误，请重新输入"); location.href("login2.php");</script>';    }    else if($row == true)    {            if($row[6]=='no')        {            echo '<script type="text/javascript"> alert("账户未激活,请到您的邮箱激活账户,账号需管理员审核后才可使用"); location.href("login2.php"); </script>';                    }        else        {            $_SESSION['email']=$email;            $_SESSION['password']=$password;            echo '<script type="text/javascript"> alert("登录成功"); location.href("index.php"); </script>';               }    }}?>