because nc-cd's don't remove only cd check, they remove memory security too, those can block functions of a trainer.
As seen in torchlight.
Hope I'm not in violation of the messageboards rules
It works for me atleast,
what program are you trying to unzip it with?
If you are using windows built-in zip manager or Winzip,
try using Winrar, 7-Zip or IZArc
(7-Zip and IZArc works for me atleast, haven't tried Winrar, but I think that should work to)