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The alarms I have scheduled never go to "OFF" automatically. However, I noticed when ever you have a notification pop-up on the screen (I.E. Facebook Notification, 20% Battery Remaining, 10% Battery Remaining), the alarm will not go off.

This also happened with my 2G, 3G and 3GS. I guess Apple still hasn't fixed this bug.
 
I use my iPhone's alarm clock to wake up on weekdays. Twice now, it has failed to go off in the past week or two. When I look at it, it's "Off," but I haven't turned it off. In fact the only time I ever launched the clock app was to set up this alarm, except when I've had to turn it back "On."

Of all the bugs, this one really bothers me. I just deleted the alarm and made a new one. Hopefully, this doesn't happen again.


Mine has dissapeared entirely twice.
 
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