#1 - Sept. 12, 2011, 10:22 p.m.
On your first trip to Leoric's passage you encounter Cain being attacked by skeletons. During the cutscene, the screen goes into a letterbox mode. When playing the game in a 4:3 aspect ratio with [x]Letterbox option enabled, there are 3 blue glowing orbs, which I assume are effects in the "fallen star hole", that bleed beyond the lower black bar.
I would imagine in a widescreen mode it's a non issue as it occurs offscreen.