I think my mini Displayport jack is broken. At first I thought it was the cable, but I switched to a new cable and still have the problem. I got thin dotted lines flashing across the screen like static on an old time TV and the picture goes black for a few seconds every few seconds. I can make it worse or sometimes better by jiggling the plug going into the Surface. My cable and monitor work fine when I plug in my wife's MacBook air.