I want to do the login page this way so that I won't be having trouble posting the username in the userpage. But everytime I try to access login.php. I get an error in firefox, that the page is not redirecting properly. What do I do? This works when I separate them into two. Into something like, login.php and verifylogin.php as the form action. But if I do it like this, I get redirection errors:

                  <?php
$host="localhost";  
$username="root"; 
$password="nitoryolai123$%^"; 
$db_name="school"; 
$tbl_name="users"; 


mysql_connect("$host", "$username", "$password")or die("cannot connect"); 
mysql_select_db("$db_name")or die("cannot select DB");






        $uname = mysql_real_escape_string($_POST['username']);
        $pword = mysql_real_escape_string($_POST['password']);

        $SQL = "SELECT * FROM users WHERE username = '$uname' AND password = '$pword'";
        $result = mysql_query($SQL);
        $num_rows = mysql_num_rows($result);



        if ($result) {
            if ($num_rows > 0) {
                session_start();
                $_SESSION['login'] = "1";
                header ("Location: userpage.php");


            }
            else {
                session_start();
                $_SESSION['login'] = "";
                header ("Location: login.php");
            }   
        }
        else {
            $errorMessage = "Error logging on";
        }









?>









<tr>
<form name="form1" method="post" action="login.php">
<td>
<table>
<tr>

<td><strong><font size="2">Login User</strong></td>
</tr>
<tr>

<td width="30" height="35"><font size="2">Username:</td>
<td width="30"><input  name="username" type="text" id="username" maxlength="17"></td>
</tr>

<tr>

<td width="30" height="35" ><font size="2">Password:</td>
<td width="30"><input name="password" type="password" id="password" maxlength="17"></td>


</tr>

<td><td align="right" width="30"><input type="submit" name="Submit" value="Submit" /></td> <td><input type="reset" name="Reset" value="Reset"></td></td>
</tr>
</form>

please help, thanks.