Hi guys, had the same issue, it kept shutting down quite frequently. Visited LG G3 store and they recommended to upgrade to latest software which I did but obviously did not fix the problem. I was not convinced with some suggestions about Reset to factory settings and then install app by app to see which one is causing the issue. Instead I decided to disable some features of G3 which are not available on some other android devices or at least not activated by default (my wife has a Samsung S5). So I disabled the Smart Notice widget and lucky me, it did not shot down for the last 10 days! (I hope it's a permanent solution, it was not really an added value widget). A bit disappointed since no official feedback from LG on this common issue.