I have had this issue for the past couple of days now and I can not figure it out. I received my new 2012 MBA last week. I imeediately popped in my mini displayport to hdmi cable to run a test video to my TV. Everything worked perfectly. Audio and video. About a week later, after getting my new desk and everything set up, I go and try again and I don't get the connection anymore. It won't show up in Display preferences and I can't "detect displays". The HDMI cable and adapter both seem to work just fine. I will have to wait until tomorrow to test at a friends house to make sure it is not either of them, but the reason I don't think so is that the MBA does in fact blink blue when I connect it, meaning that it sees something being connected to it. Also, my TV says "check source" when it is connected rather than "no signal" when not. Any help? Thanks!