3
Please check if you’re actually running your OpenGL code on the NVIDIA implementation and not on the Intel one. (E.g. glGetString(GL_VENDOR))
Might be that P-Buffers are not supported on that implementation, which should have been found earlier when querying for the P-Buffer extension.
(P-Buffers should be considered legacy code and replaced with Framebuffer-Objects when possible.)
Related post: [url]opengl - glGetString(GL_VENDOR) on hybrid graphics machines - Stack Overflow