title: Admin page on django is broken
body: <p>I've set up a django project with an admin page.  It worked perfectly for the first couple weeks of development, didn't use the admin page for a while, and when I came back to it, the admin page was broken.  No matter what I do, it won't allow me to log in.</p>
  
  <p>After entering username and PW, the admin page always says:</p>
  
  <pre><code>Please enter a correct username and password. Note that both fields are case-sensitive. 
  </code></pre>
  
  <p>I've checked the DB: the superuser exists and has is_active, is_superuser, and is_staff all True. I've used the shell to make sure the password is correct.  I've flushed, deleted, and re-created the database multiple times to make sure there's no mistake.  I've also doublechecked the middleware, urls, INSTALLED_APPS, etc to make sure they're all set up properly.</p>
  
  <p>As far as I can tell, the admin pages work perfectly except that they never let anyone log in.</p>
  
  <p>Any ideas what's going on here, or other methods for trying to debug?  I'm really baffled by this bug.</p>
  
  <p>PS: In case it matters, I'm using South for DB migrations, django-social-auth for FB logins, and separate local_settings.py for production and development (I've checked them both -- the conflict isn't there.)</p>