I have lumia 620 since past 8 months, it was working fine. I noticed from last 2 weeks it keep rebooting itself from time to time, sometime it rebooted 8-10 times in a day. I had installed some free games, has anyone same issue? Could this be due to software issue or hardware? This phone is still under warranty. Previously, it was giving messages there is something wrong with SD memory card, i have removed external memory card but still having rebooting issue. Thanks