I have used Chatter Feed component on my visualforce page . Example : The problem is that sometimes the chatter feed is loading and working completly fine while sometimes it shows the below JS error :

Uncaught ReferenceError: Ext is not defined
Uncaught ReferenceError: chatter is not defined

and therefore feed is loding but nothing in the feed is working properly like comment / Like / File etc.

I dont understand why it is happening sometimes and not everytime ... and how to get it resolved so that the problem never occurs.