I have the opposite problem of another user a few threads down. My external samsung monitor will not turn back on when i wake my MBP from sleep. I have to cycle through the inputs for it to find the display again. I'm connecting it with an Apple thunderbolt to DVI adapter then DVI cable to the monitor. I've also tried a mini DP to HDMI all in one cable to the HDMI input on the monitor and this does the same thing. Any ideas?