600ex-rt switching from slave to regular during shoot

[Jumunter]

Last night one of my 600 ex rts would switch from slave mode to regular mode during the shoot. They are all set to ttl, on camera master (a), slave (b). I would get a few shots then the slave would loose sync because it switched modes by itself. I have used this flash with no problems until now. Eventually pulled another flash (with same setting) and had no problems the rest if the night. Thoughts?

[TCampbell]

This seems odd.  Normally my units "remember" if they were in a master or slave even between usage (e.g. if a unit was last used as a slave, powered off and put away... when I power up the flash (even a few days later) the flash "remembers" that it was last used as a slave and resumes that way.)

I had considered maybe a loose wire... so I set a unit as a radio slave, powered off and opened the battery door (just in case removing batteries causes a 'reset'), closed the door and powered it back on and it STILL remembered it's a slave. 

I'd contact Canon.  I can't think of a reason or condition that would cause a slave to reset spontaneously unless it's a defect.

[Jumunter]

I know, it's very odd. I replaced by 580 ex ii's with these about three months ago and have never had an issue. They are amazing flashes. I was just curious if anyone else had any issues similar. It does remember it's assigned function from the last shoot, but I would shoot a few frames perfectly, then my assistant would tell me it wasn't firing. I look at it and it's no longer in slave mode. Tried different channels, same thing. Happened at two different locations. That's when I got fed up and grabbed a different one. I'll play with it this week and then send it in. Didn't know if it was a wide spread issue that I haven't read about. Thanks.