I think he means moving it to 0.00000002 or something similar. Zero's can cause problems sometimes. They really shouldn't matter here, but it's worth giving it a shot.
Also: I would usually work with much larger units. Objects placed at 0,0,0 lights placed at 200,100,-500 or something. J > > moving any 0 coordinates of the directional light to a tiny non-zero > > value..
