WinXP and OpenGL, as usual

Well I´m bored. Since I installed WinXP, no game that uses OpenGL had worked. No Jedi Knight 2, no Neverwinter… After a deep, long investigation I´ve discovered that the games, or windows, are totally unable to locate or start or recognize that OpenGL IS installed on the system. All the games crashes with the same error in the same dll: nvoglnt.dll. I´ve downloaded the last nvidia drivers, even tried with older versions. I purchase a Geforce 4 MX420 and the same problem… Perhaps if somebody could tell to us how can we tell the system how to locate and start correctly the OpenGL subsystem!! But I don´t understand nothing: a friend, also with XP, a Geforce 2, can play the games without any problem. Please someone that tells me how I can reinstall only the OpenGL system in WinXP? Thanx