Screen of Death
Any iPhone running iOS 7 can suffer from the problem that leads to random reboots and the white/black screen of death. Some have noticed a tendency for this to occur once the battery life indicator falls to the 30% level, and lower. Others say that the rebooting can take place when certain apps are loaded. Either way, it is an annoyance and certainly takes away from the user's enjoyment of his iPhone.
The good news is that Apple has a fix that it will be sending out along with iOS 7.1. Right now, developers are testing out the fourth beta version of iOS 7.1, so it shouldn't be terribly long before the final version of iOS 7.1 is finally released. Considering that a recent survey showed that 79% of iOS users visiting the App Store are using iOS 7, there is a large number of iPhone users that can potentially find themselves staring back at the black or white screen of death.
source: Mashable via MapleSyrup