I know this trainer is old now but I have read a lot of people asking for a steam version. Just letting you know that this trainer does work with the Steam version of the game. Just run the trainer in Administrator and XP service pack 3 Compatibility modes. I'm Running Win7 64bit, and every feature in the trainer works.
Have fun unloading clips into (Semi) Zombie brains.
I'm guessing it might just be a Win7 option. Try running it in the Service Pack 2 Compatibility mode. It might still work. Don't for get to launch the trainer in Administration mode to, or the in-game keys will not work.
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