Hello everyone,

I hope someone can help me with this as I'm a bit stumped. I moved my website (everything worked perfectly) to another domain and now something strange happens when I log in.

I type in my username and password (into admin_login.php) and press Enter.
Then a blank page appears (index.php).
When I press the Back button, I'm on the correct page and I'm logged in.

I don't know why the page is blank at first. Does anyone have any ideas?

This is my php code for both pages:

admin_login.php:

HTML Code:
<?php 
	session_start();
	if (isset($_SESSION["manager"])) {
    header("location: index.php"); 
    exit();
	}
?>

<?php 
	// Parse the log in form if the user has filled it out and pressed "Log In"
	if (isset($_POST["username"]) && isset($_POST["password"])) {

	$manager = preg_replace('#[^A-Za-z0-9]#i', '', $_POST["username"]); // filter everything but numbers and letters
    $password = preg_replace('#[^A-Za-z0-9]#i', '', $_POST["password"]); // filter everything but numbers and letters

	// Connect to the MySQL database  
    include "../storescripts/connect_to_mysql.php"; 
    $sql = mysql_query("SELECT id FROM admin WHERE username='$manager' AND password='$password' LIMIT 1"); // query the person
  
	// Make sure the person exists in the database
    $existCount = mysql_num_rows($sql); // count the row nums
    if ($existCount == 1) { // evaluate the count
	     while($row = mysql_fetch_array($sql)){ 
             $id = $row["id"];
		 }
		 $_SESSION["id"] = $id;
		 $_SESSION["manager"] = $manager;
		 $_SESSION["password"] = $password;
		 header("location: index.php");
         exit();
    } else {
		echo 'The information is incorrect, please try again. <a href="index.php">Click Here</a>';
		exit();
	}
	}
?>
index.php:

HTML Code:
<?php 
	session_start();
	if (!isset($_SESSION["manager"])) {
    header("location: admin_login.php"); 
    exit();
	}

	// Be sure to check that this manager SESSION value is in fact in the database
	$managerID = preg_replace('#[^0-9]#i', '', $_SESSION["id"]); // filter everything but numbers and letters
	$manager = preg_replace('#[^A-Za-z0-9]#i', '', $_SESSION["manager"]); // filter everything but numbers and letters
	$password = preg_replace('#[^A-Za-z0-9]#i', '', $_SESSION["password"]); // filter everything but numbers and letters

	// Run mySQL query to be sure that this person is an admin and that their password session 
	// var equals the database information

	// Connect to the MySQL database  
	include "../storescripts/connect_to_mysql.php"; 
	$sql = mysql_query("SELECT * FROM admin WHERE id='$managerID' AND username='$manager' AND password='$password' LIMIT 1"); // query the person

	// Make sure this person exists in the database
	$existCount = mysql_num_rows($sql); // count the row nums
	if ($existCount == 0) { // evaluate the count
	echo "Your login session data is not on record in the database.";
    exit();
	}
?>
Any help/ideas would be much appreciated.