I had been using Ubuntu 14.04 with my 54250WYKH1 flawlessly for a couple months until I applied the latest Ubuntu updates at which point video was completely broken. Ubuntu seemed to boot fine but lost video signal at the point at which the windows manager would normally start.
I troubleshooted the issue for hours over the weekend but never got it to work again so I wound up re-installing Ubuntu.
Posting this as a warning other folks and wondering if anyone has more information?