There seems to be a little bug that affects a small number of MacBook Pro (with dual graphic card) machines; the display would turn blueish when the discreet graphic is in use by way of the Automatic Graphic Switching.

User [daywalkerdha](https://discussions.apple.com/people/daywalkerdha) shared a fix, but I’ve included some extra steps to ensure its effect:

> 1. Close all running apps, unplug the power cable.
> 2. Disable automatic graphics card switching while in battery-mode (in System Preferences).
> 3. Reboot, and reset the PRAM (Hold Option-Command-P-R keys, continue until second startup time).
> 4. Connect the power cable after the boot sequence finish.
> 5. Enable automatic switching again.

You can also try [resetting the SMC](http://support.apple.com/kb/HT3964?viewlocale=en_US&locale=en_US), or [update Nvidia’s CUDA Driver](http://www.nvidia.com/object/macosx-cuda-5.5.24-driver.html) if you want to be thorough, but [daywalkerdha’s](https://discussions.apple.com/people/daywalkerdha) solution worked perfectly for me.

*Update:* The same problem reappears in Yosemite (build 14A261i), and the same fix seems to have worked accordingly.