This just started a week or so ago. My Thunderbolt display will go black for 2-3 seconds every hour or so. My secondary display is fine; it doesn't reorient to be the primary display; the TB display comes back on and all is fine. Today, after a reboot though, the TB display blanked out and stayed that way til I unplugged it from the Mini and plugged it back in. But then I had to go back through and resize and reposition all of my windows. I'm wondering if this could be an issue with the graphics card on the Mini, or with the TB display? I have AppleCare on the Mini, but I dread having to lug both units an hour away to a Genius Bar to get them looked at. Anybody ever see this issue before?