While shooting some casual photos today I noticed some odd behavior on my 7D. On trying to review a couple of photos I noticed the camera didn't respond and and nothing displayed on the LCD. I took 3 or 4 more photos and then the camera went dark, as if it had been powered off. I removed all batteries for about twenty minutes Then powered it back up and I was able to view images on the LCD again. I called it a day for that camera and put it away to use another body. The only thing that I did different today was that I had my 580EX flash attached for fill light. I usually don't use flash with this camera. I did check the batteries and both were at about 57% (I use a battery grip on this camera). I also did have some card read errors a couple weeks ago but powering the camera off and back on seemed to resolve that. It doesn't seem likely that a faulty card would power off the camera - I am using San Disk if that is important. Has anyone seen this behavior before? Any help would be appreciated.