i am having a problem with sheet metal  drawings.  i am getting lines showing up in drawing views that shouldn't be there.  if i zoom in, they disappear.  if i zoom out, they show up.  the problem is  that they show up on prints.  please see the attaached pictures.  same view, just that i zoomed in closer on teh one that no lines show up in.  there is no interference between parts, hidden edges are invisible...

thanks for any insight