Did anyone find a solution to this? I am using the Device lock Security code (= boot and autolock password) because I can't turn that off. If I could turn that off, I suspect that might solve the erratically working alarm clock as well. I don't dare removing my Mail for Exchange account and possibly that forces me to use the password (I am not sure)?

Very often when the phone is off, at alarm time the phone will just boot to the password screen and get stuck there. Or sometimes it works normally and sometimes it lets out a short alarm sound and then stops.

If there is anything I can try to get the alarm clock working and booting reliably, that'd be just great.