My old slow windows mobile phone would do this sometimes. I would have calendar events throughout the day. Once in a while it would lock up and require a battery pull. When I put the battery back in, every single alarm from the past few weeks would go off at the same time. It normally took about 2 minutes to boot up, but with all these alarms going off at the same time, it would take almost 5 minutes before I could even hit any button.