With the coming of the new year of 2011 brought a very annoying bug with the iPhone that rendered the daily alarms useless.
The problem made owners wake up late for the first days back to work for 2011 and some missed plains or trains as the alarms failed to go off.
Apple said however these problems would rectified from 3rd January which was true for some people, but not all, including my girlfriends iPhone.
So in true IT fashion I basically “turned it off and back on again”. Meaning I deleted the currently alarms and recreated them, which appeared to solve the problem.
So if you are still having problems with your iPhone try giving it a go, delete all alarms currently entered and recreated them.
Hope it helps.