Firefox 3.6.23, trying to load this page:
http://docs.sencha.com/ext-js/4-1/#!/api

The green/grey spinning gear image appears, but docs app never finished loading.
I can see this error in Firebug:
i.getAllResponseHeaders() is null
http://docs.sencha.com/ext-js/4-1/extjs/ext-all.js
Line 38

Is anyone else experiencing this?