I have had my 600EX-RT for about a year with no issues. Last night I was using it in a nightclub on very low power for just a touch of flash fill. On three occasions in a period of about five minutes it just stuck on and looked like a bright movie light. It turned off on it's own, but did it three times in a row. Not real great in a very dim nightclub! I had a diffuser on it and it was glowing like a very bright nightstick. I was able to cover it with my hands to avoid further distractions to the audience. It was mounted on the hot shoe of my 5D3 at the time. Has anyone had this happen to them? I assume I should just send it to Canon, but it was fine for the last hour after that. Any thoughts? Thanks so much. this is my first post here. Craig