I also have a site doing this. the little spinner just spins. I don’t get the error off the side like you did for image 0777.jpg
I have tried turning off all plugins (at the same time)
I have tried adding define(‘CONCATENATE_SCRIPTS’, false ); to wp-config
I have not tried changing themes or deleting all items in the library
Okay…. I just tried changing themes to the 2014 WP theme and that fixed the problem. My theme is a child of mystile by woothemes
I tested the base theme and it’s fine, so the problem is in the child (hey, I have a “problem child”!) — looked in functions.php for the child theme and saw a google analytics script there (which worked before 3.9.1) – I removed that script and problem solved.
I hope that helps you in some way 🙂
