I was out in the yard doing some macro shots (using live view, green button metering). I had just viewed some of the photos on the lcd, and was flipping across images and this came up. I had to pull the battery to reset it and it's been fine since. The one recent change is I got a new SD card, a 32GB class 10 which I believe I needed the latest firmware to support on this body. I've been using the card/firmware for a month or so and the camera for 18 months with no problems. Any ideas? My plan is to just keep on keepin' on and hope it doesn't come back. If it becomes reproducible then I should be able to isolate the scenario that causes it.