Internal Server Error accesing the main page

edit

I get this error in different urls (accessing a question, the main page like in this one or when signing in):

Traceback (most recent call last):

File "/usr/local/lib/python2.7/dist-packages/Django-1.4.2-py2.7.egg/django/core/handlers/base.py", line 111, in get_response
  response = callback(request, *callback_args, **callback_kwargs)

File "/var/www/askbot-devel/askbot/views/readers.py", line 229, in questions
  return render_into_skin('main_page.html', template_data, request)

File "/var/www/askbot-devel/askbot/skins/loaders.py", line 131, in render_into_skin
  render_into_skin_as_string(template, data, request),

File "/var/www/askbot-devel/askbot/skins/loaders.py", line 123, in render_into_skin_as_string
  return template.render(context)

File "/usr/local/lib/python2.7/dist-packages/Coffin-0.3.7-py2.7.egg/coffin/template/__init__.py", line 55, in render
  return super(Template, self).render(**context)

File "/usr/local/lib/python2.7/dist-packages/Jinja2-2.6-py2.7.egg/jinja2/environment.py", line 894, in render
  return self.environment.handle_exception(exc_info, True)

File "/var/www/askbot-devel/askbot/templates/main_page.html", line 1, in top-level template code
  {% extends "two_column_body.html" %}

File "/var/www/askbot-devel/askbot/templates/two_column_body.html", line 1, in top-level template code
  {% extends "base.html" %}

File "/var/www/askbot-devel/askbot/templates/base.html", line 46, in top-level template code
  {% block body %}

File "/var/www/askbot-devel/askbot/templates/two_column_body.html", line 5, in block "body"
  {% block content%}

File "/var/www/askbot-devel/askbot/templates/main_page.html", line 13, in block "content"
  {% include "main_page/tab_bar.html" %}

File "/usr/local/lib/python2.7/dist-packages/Jinja2-2.6-py2.7.egg/jinja2/utils.py", line 473, in __setitem__
  del self._mapping[self._popleft()]

KeyError: 'main_page/headline.html'

Other times the error is the same until {% extends "two_column_body.html" %} and then ends like this:

KeyError: 'two_column_body.html'

It's not usual to get this error, but dometimes it just happens.