Pull the screen and make sure the connection are clean and secure. Also, make sure there isn't anything on the battery like a misplaced screw. This usually happens because something is putting upward pressure on the screen. If there aren't any screws or other debris, take a look and make sure you have the speaker assembly in correctly.
If none of that works, try your old screen and see if it does the same thing. It very well could be a bad screen. If your old screen does the same thing, its possible that it could be a Touch IC issue.