Default Time Resets at whenever battery dies

Hi Everyone!

I recently switched from S4 to G2 and I am loving it, but I am facing 2 problems.

1- Time is set to some random value whenever the battery dies, usually sometime 3-5 days ago. It doesn't happen when I restart or turn on the phone after even 2-3 hours without getting battery to 0%.

2- Sometimes when I unlock the screen, it automatically locks again, it happens 3-4 times in a row, and then settles itself.

Thanks.

Best Regards.