Nette sandbox NServiceCreationException problem

Hi!
I've just downloaded Nette and trying to test sandbox app.
checker.php gives OK result.
But, when i'm trying to load sandbox i'm receiving:

*NServiceCreationException
Service 'authenticator': Object of class stdClass could not be converted to string
Call stack ▼
1.    ...\libs\Nette\Config\Compiler.php:127 source ►  NConfigCompiler:: parseServices (arguments ►)
2.    ...\libs\Nette\Config\Compiler.php:96 source ►  NConfigCompiler-> processServices ()
3.    ...\libs\Nette\Config\Configurator.php:235 source ►  NConfigCompiler-> compile (arguments ►)
4.    ...\libs\Nette\Config\Configurator.php:182 source ►  NConfigurator-> buildContainer (arguments ►)
5.    ...\app\bootstrap.php:29 source ►  NConfigurator-> createContainer ()
6.    19:
      20: // Enable RobotLoader - this will load all classes automatically
      21: $configurator->setTempDirectory(dirname(__FILE__) . '/../temp');
      22: $configurator->createRobotLoader()
      23:     ->addDirectory(APP_DIR)
      24:     ->addDirectory(LIBS_DIR)
      25:     ->register();
      26:
      27: // Create Dependency Injection container from config.neon file
      28: $configurator->addConfig(dirname(__FILE__) . '/config/config.neon');
      29: $container = $configurator->createContainer();
     30:
     31: // Setup router 32: $container->router[] = new NRoute('index.php', 'Homepage:default', NRoute::ONE_WAY);
     33: $container->router[] = new NRoute('<presenter>/<action>[/<id>]', 'Homepage:default');
7.    ...\www\index.php:16 source ►  require (arguments ►) *

What does it mean and how can i solve this problem?
Thanks!