I downloaded Black as an xbox original.  Whenever I get halfway through the last level (Gulag), my gun disappears although it will still fire and then I am unable to switch guns or throw grenades.  Is this glitch happening to anybody else?  Any advice?  I would like to finish the game.

Same problem here. I'm on the last level and can't finish it because that happens. When I'd use the disc before it'd do the same thing. Seems to be random for me though...but still ruins my experience. Think we could get a refund since the full game isn't accessible?