title: Error on "production" environment on Symfony2
body: <p>I´m currently developing a web site using Symfony2.</p>
  <p>On 'dev' environment everything works just fine, but when I try to access to the system with the <code>DEBUG</code> parameter on <code>FALSE</code> (trough app.php which invokes the appKernel with debugger disabled) the system throws a &quot;<code>500 Internal Server Error</code>&quot; when I try to load any section of the system.</p>
  <p>I've already cleared the cache and warmed it up and this error keeps showing up.
  I'm working with the standard distribution of Symfony (didn't change anything but the bundle I created) and this server: <code>Apache/2.2.17 (Win32) mod_ssl/2.2.17 OpenSSL/0.9.8o PHP/5.3.4 mod_perl/2.0.4 Perl/v5.10.1 installed trough XAMPP</code></p>
  <p>How can I make the production environment work keeping the debugger disabled?</p>