This sounds really weird, I have never experienced this issue while using Ubuntu. My guesses are that you either have a bad USB cable or you accidentally blocked screen.
Can you test your Edison with a different USB cable? Does it make a difference?
Check http://stackoverflow.com/questions/4367669/the-gnu-screen-is-unresponsive-seems-blocked, do you think something like that could be happening to you?
Peter, Thanks for the solid link. I will give this a go when I get home.
Not specifically, I updated some dependencies from another site I found highlighting a similar problem. This seemed to work, but I have the site Peter mentioned on standby if I find otherwise.