Hello, im nubie user - android. Nexus 5 is my first android. Now i have a problem. FYI, my phone 's great. No lag no drain battery etc. But sometimes it shutdown by itself. After shutdown, system not responding is poping out. I'd asking to LG center services, power button still good. Then, when i connect to my wifi, things happen again. But when not in wifi connection and cellular data connection, this phone do great. I dunno what should i do now ? Pls help me .. nexus5 latest os updates..