Me and my brother have a very similar issue. Our Gabb Z2 phones are continuously crashing. I am not longer able to send messages, and I cannot scroll up in a conversation. If I try to type something, it crashes. If I scroll up in a conversation, it crashes. The calls randomly disconnect or fail and I am unable to call someone back. Every time I try, it simply stops and ignores my requests to call. My signal randomly goes out. It randomly displays the 'no sim card' message, even though I'VE NEVER REMOVED IT.