mid 2011 11" I use it connected to a 55" vizio tv in closed clamshell mode probably 75% of the time. It's connected via minidisplayport to vga cable. It's worked perfectly since November of '11 set up this way. Tonight I was noodling around and the pointer drifted up to the mirroring icon on the options menu, for some damn reason I tapped and brought up display preferences. In display preferences the resolution was set to "best for this display"? the other option was "scaled". I apparently clicked scaled (part of my problem is I use tap to click and chose scaled by tapping when I was trying to move my pointer). The result is clamshell mode is broken, really it seems that the output of the mba to the tv is broken in general. It no longer gives me the option to choose "best resolution for this display" If I close the mba I get an "invalid format" message on the tv or sometimes "no signal". The only way to output to the tv is to have the display open and mirror it to the tv with the resolution set to 1920x1080 60 htz (but what's displayed on the screen isn't 1920x1080 but the built in lcd's res). I vaguely remember having to set the resolution to 1920x1080 at 59 hertz when I first connected to this tv way back when, but that option isn't there to choose now, only 60, 70, 72, 75. I've restarted, unplugged everything and replugged, reset pram, This is driving me nucking futs. HELP.