Invisible text in the "Edit Page"

Hi,

My website is on Wordpress 4.1.1

When I try to edit some of my website pages, I don't see any text in in the Visual Editor. When I highlight the text of the page, the text shows up. So, for some reason the text in the Visual Editor is set to white. The buttons in visual editor are also missing.

Here's a screenshot: http://screencast.com/t/P2w5Wi6L

This happens on majority, but not all of my pages.

I've tried clearing my browser's cache, and switched browsers - no help.
I already have define('CONCATENATE_SCRIPTS', false); in my wp-config.php

What else should I try?

Thanks,