Hey guys, longtime lurker here. Had to register to post this because I need some help desperately. So 1 week ago I bought a new Haswell rMBP 13 (2.4GHz i5, 8GB, 256GB), and today I tried to connect it to my external monitor (Acer P235H - from an old PC) through HDMI. When I plugged the HDMI cable into my rMBP, the screen flickered as if it detected the monitor, but the monitor kept saying "Cable not connected". Tried going into System Prefs>Displays>Detect Display, but when I pressed Detect Display, nothing showed up. Unplugged and replugged the HDMI cable and toggled the power for the external monitor, but still no luck. Then I tried googling the issue, and found a 24 page(!!!) thread over at apple discussion forums full of ppl having the same issue. Tried some of the fixes described there, including resetting PRAM and SRAM, toggling the external monitor power supply on and off, sleeping the rMBP then connecting the HDMI cable, full shut down and connect the monitor only after startup etcetc. Did not try the gfxstatus one as this rMBP only has intel iGPU. The monitor and HDMI cable are both working, plugged them into a windows laptop and a nexus 10 (with an adaptor) to check. For both the windows laptop and the nexus 10, the display was mirrored just seconds after plugging the HDMI cable in. I currently do not have any HDMI to thunderbolt adaptors, so I cannot check whether its a problem with the HDMI port or not, but I am certain the rMBP detects the monitor (but it does not show up in the displays section in system prefs) because every time I plug the HDMI cable in, the rMBP screen flickers, and when I toggle the external monitor on and off, the screen flickers twice. I also do not have any other external displays to test. I will be going down to the store that I bought to from sometime this week to see whether they can help, but in the meantime any suggestions?