[phpAuction] Errore di installazione

Sto cercando di installare phpAuction GPL versione 3.3 ma arrivati allo step 5 ricevo una segnalazione: Errore 500 internal server error
Di seguito il codice che tenta di eseguire:

Codice PHP:

---

define("INCLUDED",1);
session_start();

require('../includes/messages.EN.inc.php');

if($_POST[action] == "next")
{
$STEP = 5;
$_SESSION["STEP"]=$STEP;
Header("Location: install5.php");
}

#// ########################################################
#// Create database
#// ########################################################
mysql_connect($_SESSION['DBhost'], $_SESSION['DBuser'], $_SESSION['DBpassword']);

/*if($_SESSION[DBaction] == "newdb")
{
mysql_create_db($DBdb);
$DBCREATED = TRUE;
}
*/

mysql_select_db($_SESSION['DBdb']);

$CURRENT = getcwd();
if($_SESSION[OPERATINGSYSTEM] == "Windows")
{
$SQL = str_replace(strrchr($CURRENT,"\\"),"\\sql\\",$CURRENT);
}
else
{
$SQL = str_replace(strrchr($CURRENT,"/"),"/sql/",$CURRENT);
}

include $SQL."dump.inc.php";

while(list($k,$v) = each($query))
{
@mysql_query($v);
}

#// Insert some default values into the database
$query = "UPDATE PHPAUCTIONXL_settings SET
sitename='".$_SESSION[SETTINGS][sitename]."',
siteurl='".$_SESSION[SETTINGS][siteurl]."',
adminmail='".$_SESSION[SETTINGS][adminmail]."'";
$res = @mysql_query($query);
if(!$res){
print "$ERR_001<BR>$query<BR>".mysql_error();
exit;
}

$BG[1] = "#EEEEEE";
$FONT[1] = "#CCCCCC";
$BG[2] = "#EEEEEE";
$FONT[2] = "#CCCCCC";
$BG[3] = "#EEEEEE";
$FONT[3] = "#CCCCCC";
$BG[4] = "#EEEEEE";
$FONT[4] = "#CCCCCC";
$BG[5] = "#00CC00";
$FONT[5] = "#FFFFFF";


require "installheader.php";
?>


---

Da cosa può dipendere?
Grazie