I have problems with speed under OpenGL

I have GeForce3 Ti 200 and last drivers from nVidia are installed. I overlooked video card using RivaTunner. After that all OpenGL applications began to work very slowly. I put default value for core clock and memory clock, but nothing changed…
Can somebody help me with something?
Than you.

Does everything you run, run slowly? Or just one program?

Any OpenGL application run slowly, but DirectX applications run normal… I installed DirectX 9, but I think that it can’t influence OpenGL.