This line would only start the header if it was throwing an error. So you need to figure out why connecting to the database is causing an error:
$ProductsDb = mysql_pconnect($hostname_ProductsDb, $username_ProductsDb, $password_ProductsDb) or trigger_error(mysql_error(),E_USER_ERROR);
If you can give me a URL to reproduce the problem and FTP access I can try to debug it and see what the actual error is. The second line with the header redirect is not the problem. You can't redirect after code above throws an error, so the real problem is the error in the database connection.