Sweet - I have been having a small panic attack over the last week because my phone kept randomly shutting itself off. It was one of the reasons I did a fresh load, but yesterday an today it kept shutting off again randomly.
Then It shut off while my son was "flicking open" the Zippo Lighter app and suddenly it was like a light went off. I did a few experiments and lo and behold the battery was shifting in the phone.
I guess after a year and a half the springs on the contacts are not as tense as they once were and when the phone was bumped it would lose contact and shut off. Well a piece of folded paper and some double sided tape did wonders and now I can shake the pone and have it stay on!