NuGardt Software

I took all the mods out of the folder and placed them on the desktop and tried running a demo without the mods in there and it still got the same error

When Itry to launch demofrom Seismovision, starts to load and then crashes and I get this error: WARNING: Could not find material 'american' Loading 'ui_mp/ingame.menu'... Loading 'ui_mp/ingame_controls.menu'... Loading 'ui_mp/ingame_options.menu'... Loading 'ui_mp/ingame_system.menu'... Loading 'ui...