Can't add links, media or edit in Text mode

I’m having problems out of the blue with one of my WordPress sites. A few things that have been happening:

1. I can’t view or edit in text view, only in html view. When I click on the text tab, it stays in visual view.
2. While in visual view if I highlight a phrase that I want to add a link to and click on the link button, nothing happens.
3. I also can’t add media. When I click on the media button no window pops up to add any.

I’ve tried re-installing WordPress (have the latest version). I also deactivated all my plugins in case one of them was buggering it up but it still wouldn’t work. I also changed to a default theme to see if the theme was causing the issue. Still not working.

It happens in Chrome, Firefox and IE (all latest versions with cache cleaned).

Any suggestions?