try setup-a/v settings video output set to hdmi (if you are using hdmi)- try changing automatic resolution to enabled. see if that does the trick. If not, set automatic resolution back to disabled and mode to 720p--- you could also try changing refresh rate, one or other of these settings should get you to where you can work on the box comfortably. after you have all the menus etc. setup, you can then change these settings back till you get the best video image
As well as the airplay plugin itself?