Portail PHP

unset($login,$pwrd,$id); 
session_start();        <--- La FAMEUSE LIGNE 17
session_register("login","pwrd","id"); 

if($logout==1){ 
session_destroy(); 
header("Location: "  .$PHP_SELF); 
} 

require(´error_inc.php´); 
require(´config_inc.php´); 


function auth($log,$pass){ 
global $t_user; 
$query = "  select id from "  .$t_user." where email="".$log."" and pass="".$pass."" "  ; 
$result = MYSQL_QUERY($query); 
if(mysql_num_rows($result)>0){ 
$id=mysql_result($result,0,"id"); 
@mysql_free_result($result); 
return $id; 
}else{ 
@mysql_free_result($result); 
return 0; 
} 
} 

if(auth($login,$pwrd)!=0){ 
header("Location: user_menu.php?PHPSESSID=".$PHPSESSID); 
} 
if($REQUEST_METHOD=="POST"){ 
if(isset($lo)){ 
$log=htmlspecialchars($log); 
$passwrd=htmlspecialchars($passwrd); 
$au=auth($log,$passwrd); 
if($au>0){ 
$login=$log; 
$pwrd=$passwrd; 
$id=$au; 
header("Location: user_menu.php?PHPSESSID=".$PHPSESSID); 
}else{ 
require(´header_inc.php´); 
print "  <p>".$err[1]."</p>"; 
} 
} 
}else{ 
require(´header_inc.php´); 
} 
?  > 
<  form name="form1" method="post" action="" >   
<  table border="0" cellspacing="2" cellpadding="0" align="center"> 
<  tr align="center"> 

<  td height="20" align=right><b>Log In</b></td> 
<  td height="20"> </td> 
<  /tr> 
<  tr> 

<  td align="right">Your Email:</td> 

<  td align="left" height="20"> 
<  input type="text" name="log" size="15"> 
<  /td> 
<  /tr> 
<  tr> 

<  td align="right">Password:</td> 

<  td align="left" height="20"> 
<  input type="password" name="passwrd" size="15"> 
<  /td> 
<  /tr> 
<  tr> 

<  td align="right" valign="top"> </td> 

<  td align="left" height="20"> 
<  input type="submit" name="lo" value="Log In"> 
<  br> 
<a href="forgot.php"><font color=blue size=1>Forgot your password?</font></a> 
<  /td> 
<  /tr> 
<  /table> 
<  /form> 
<  ? 
require(´footer_inc.php´); 
?  >