Originally Posted by conky
KWin doesn't use OpenGL 3.0. Mesa doesn't support OpenGL 3.0 yet. There are plans to move KWin compositing to OpenGL 3.0 for KDE 4.7, but that's in the future. Nvidia's drivers share most of their code base with the Windows driver. OpenGL 3 and 4 work fine with Nvidia's linux drivers.
Well yeah, you are right, i made mistake. Kwin uses opengl 1 as its base, but the blur plugin uses opengl 2.0. It looks like different hardware combinations are not supported well. more or less, we must know the answer from nvidia developer, so see whats really wrong with nvidia driver.