ns doesn't support software mode as a video mode.
start a standard game of half-life which does. Then go into video settings and select openGL as your video mode. d3d sux and software won't work. Then save the settings and exit HL, then NS should start ok.
If your video card won't load this mod it's time to get new drivers and/or spend 40 bux on a geforceMX card or something with good opengl support.
EDIT: See this other thread for more info:
http://www.unknownworlds.com/forums/in...showtopic=81251