An apparent bug causes the screens on some iPhone 5s models to briefly flash to blue when you try to switch apps from iWork and then the phone restarts.
via PCWorld http://www.macworld.com/article/2053355/some-iphone-5s-users-sing-the-blues-over-iwork-bug.html#tk.rss_all
via PCWorld http://www.macworld.com/article/2053355/some-iphone-5s-users-sing-the-blues-over-iwork-bug.html#tk.rss_all