Since last december’s update, the two WordPress blogs I’m using at work have a similar issue : when I’m on the edit page of a post, clicking on the media button does nothing (same with “featured image” link). Everything else is working fine.
One of these blogs is a self-hosted WordPress, the other other is a WordPress.com blog.
I tried turning off plugins, it didn’t work (and the fact that I’m having the issue even on a WordPress.com blog seems to imply that it’s not a plugin issue).
When I access the sites at home, or on my professional computer but with another internet access than my office’s access, everything works.
The guys in charge of our network can’t figure out what to do. We tried using Firebug for clues about what’s being blocked, with no luck.