I had this a LOT with the AFS update. My issue was when my phone was in one location it crashed when it was connected to WIFI only. It was very strange. I'm working around it but wiping network settings and connecting to WIFI and NOT resetting the phone. If i restart the phone, it would crash when connected to WIFI in this one location. Very strange issue. I hope you get yours resolved - post back if you do. I'm sure it was the AFS update as this started the day I updated.