I've installed a Drupal Site on Amazon EC2 cluster. It was OK until I'd moved the site to Amazon Virtual Private Cluster. It works properly at the first time but it fails after first reboot. I realized that index.php file was changed and install.php file was created after reboot. I think Drupal tries to make a new installation when it's not able to see the database. When I copied original index.php file it worked again until next reboot.

How could I solve this problem? Help please!