Trying to see if anyone has had this issue with the 7D. While doing some night shooting this week I had this problem, took a shot , maybe a 10 second exposure, the shutter released as normal after the shot was finished. A few moments later I looked at the back of the camera and noticed the busy light was still red. I tried to view the menu, could not do that, tried to power the camera down with the on/off switch, that would not work. I had to pull the battery and reinsert it and everything worked fine. I took about 10 more shots after that and did not have any problems. I was using a Canon 100-400L
IS lens. The camera probably has maybe 50 or 60,000 clicks om it.