Macbook Pro Retina and Dell u3011 video driver problem i have a macbook pro retina with OS X 10.8.4 (12E55) , and i'm connecting it to a dell u3011 monitor using a mini-display to displayport cable , it was working great until today whenever i connect the cable my monitor goes to energy save mode , i thought this was a cable problem so i bought a new one and the problem still remains , i connected to the monitor using HDMI and its working fine , is it a video driver problem?
Incredibly late answer, but I had the same issue and what worked for me was to reset the NVRAM.