Warning: require_once(./includes/bootstrap.inc) [function.require-once]: failed to open stream: Invalid argument in C:\Program Files\wamp\www\drupal\index.php on line 15

Fatal error: require_once() [function.require]: Failed opening required './includes/bootstrap.inc' (include_path='.;C:\php5\pear') in C:\Program Files\wamp\www\drupal\index.php on line 15