I'm getting an error on page "update_account.php"

When I try to update a user's account info I receive the following error:

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '' at line 3

Line 3 refers to "auth_user.inc.php", so I assume this error is really talking about the code below:

<?
session_start();
if ($_SESSION['user_logged'] == "" || $_SESSION['user_password'] == "")
{
     $redirect = $_SERVER['PHP_SELF'];
     header("Refresh: 5; URL=user_login.php?redirect=$redirect");
     echo "You are currently not logged in, we are redirecting you, be
          patient!<br>";
     echo "(If your browser doesn't support this, <a
          href=\"user_login.php?redirect=$redirect\">click here</a>)";
     die();
}
else {}
?>

Anyone have any ideas as to why I would receive this message?