--- Operating System, Graphics card ---
Mac OS X Mountain Lion (Hackintosh). GTX580, GTX 560Ti, Intel 4000.

GTX580 and GTX 560Ti are used for CUDA rendering. Intel 4000 is hooked up to the display.

--- Blender version with error, and version that worked ---
2.66.6 (r56271) and just tested on latest build from buildbot (2.66-r56501). Both produce the same error.

--- Short description of error ---
Any project I open, old/new, shows any colour wheels as can be seen in the attached image. Moving the point on the wheel seems to work as normal, so it just appears to be a problem with displaying the colour spectrum on the wheel. Every now and then when I zoom in/out on the compositor, the correct colours flicker on for an instant, but then it goes back to what can be seen again.

I've just recently switched from using my GTX 560Ti for driving my display to the Intel 4000 graphics and I believe that's when I started seeing the problem. To test this, I just switched back to one of my GTX cards for my monitor and the colour wheel is displaying correctly again. So, it looks like it's a problem with the Intel 4000 internal graphics.

I realise that with using a Hackintosh, I could have created the problem myself by not having the correct boot flags/kexts, but all my other applications seem to work fine with the Intel graphics.

--- Steps for others to reproduce the error (preferably based on attached .blend file) ---
Open any blend on a machine using Intel 4000 graphics to drive the display and add a node with a colour wheel.