I bought my MBP(Mid 2012) about 3 weeks ago and everything was fine until I installed an update(update 2.0 from AppStore) which said it could improve the graphic performance. However, after the update was installed, my screen become blueish(more cooler) when the graphics card switches from HD4000 to GT650M.I have searched some solutions but no one works. Finally I thought now that the problem emerged after the update, maybe the update was not installed correctly. So I went to the apple support website and download the update 2.0 for Macbook pro/air(Mid 2012) and installed it again. Everything becomes normal now. So for those who suffer this graphic card switching problem, you can try my way. Just download the update and install it again. Here is the link: http://support.apple.com/kb/DL1609 Good Luck!