Another thing... I know this is obvious to most.. I never wind my automatics, I rotate them im my hand/wrist to get them started, then wear them. It takes a little finesse to get a feel for it. I've tried to show others how an automatic works and showed them how to wind it by rotating it to get the balance weight to spin but some just don't seem to get it.
Again, I know this is so juvenile, it just seems strange that this would happen twice for you... that they'd they work for several hours/days, then stop.