I've never had a problem with either Symfony2 or Vagrant before this point and I'm absolutely lost as to what is happening.
Without any warning my environment died completely and will only produce the following error:
failed to open stream: No such file or directory in /var/www/project-web/vendor/twig/twig/lib/Twig/Loader/Filesystem.php line 130
My first guess is you have run it locally first and the paths are in the cache. If so it should be fixed by running the following in your vagrant environment:
php app/console cache:clear
--env=prod if you are running the app.php rather then app_dev.php.