This bug was likely introduced with some Half-Life patch by Valve way after the release of "Poke646: Vendetta", but it's fairly easy to fix. Go into your "steam/steamapps/username/half-life" folder and delete both the "vendetta" and "vendetta_german" folder. Now do a complete reinstall of "Poke646: Vendetta" and restart the game. Please note that all your savegames and progress will be lost in the process!


