Error session

[killerchess]

Estoy usando el clásico access.php asi:
<?php
session_start();
if (isset($_SESSION['check']))
{
if($_SESSION['check'] != "s")
{
header("Location:index.html");
exit();
}
}
else
{
include "index.html";
exit();
}
?>
Pero me esta arrojando el siguiente error:

Warning: open(/tmp\sess_cf6aa82dd96b59f1ddb9b049fe18d144, O_RDWR) failed: No such file or directory (2) in access.php on line 2

Warning: open(/tmp\sess_cf6aa82dd96b59f1ddb9b049fe18d144, O_RDWR) failed: No such file or directory (2) in Unknown on line 0

Warning: Failed to write session data (files). Please verify that the current setting of session.save_path is correct (/tmp) in Unknown on line 0

Verifique el path que me dicen al final y esta bien.
Gracias de antemano.