One of the features I was most looking forward to using with Mountain Lion was AirPlay Mirroring. Well, the first time I tried it (on my spring 2011 MBP and ATV3, using a 32" 720p RCA televsion), only the upper lefthand corner of the screen would appear on my TV, no matter how which display resolution I selected (I tried them all): http://i.imgur.com/zLHH7.jpg Well, I restarted my computer and tried again today and, to my delight, it was working! http://i.imgur.com/TRNll.jpg Ten minutes into using it, however (I was trying out playing the Sims 3 on my TV to see how laggy it was, and was pretty impressed), the picture on the TV screen froze and AirPlay turned itself off. I tried turning it on a couple of times with no response from the ATV, then restarted the ATV and my MBP only for it to continue to show only the upper lefthand corner. Has anyone else been experiencing this, or are there any ideas as to why this could be the case? Could it be my TV that's the problem (a friend suggested it may be the TV's size/resolution, but it's worked fine with my ATV up until now)?