More info please
I'm running FreeBSD 4.7 STABLE and have a GeForce4 MX440 in a board with a Via chipset (not sure which), OpenGL apps don't work for me either. Or, to be more precise some work and some other don't.
Please post the results of 'ls -l /usr/X11R6/lib/*GL*', 'ls -l /dev/nvidia*' and of 'ldd /usr/X11R6/bin/glxgears'
Maybe we can solve this puzzle together