On one remote client machine, PROC proc = wglGetProcAddress("wglChoosePixelFormatARB"); returns NULL and I get a crash. Since it is remote I cannot debug it. Any tips? This is standard OpenGL without shaders. Perhaps it is because I did not include .dlls or .libs in the distribution, only the .exe?

wglGetProcAddress only works if you have a valid OpenGL context. If it returns NULL, then very likely the context is not valid.