How do you fix the flickering env_sun which occurs while looking directly at it?

[Acecool]

Does anyone know how to fix flickering sun while you're looking directly at it? Or is this just a glitch with the source engine that can't be solved without Garry diving into it? I can set the sun very small and use the env_skypaint to paint the outline, but I like the additional orb effect.. Many thanks in advance.