Xperia 1 - auto reboot problem ~ HELP!!!

[#1]

Hi all,  I have Xperia 1, and in the recent month, the phone occasionally (once or twice a week) shuts down and reboots by itself.  What's the solution?

Please please help me

[#2]

Have you installed any 3rd party software?

How much free memory do you have on the phone?

[#3]

I have SPB Time and SPB Mobile Shell on my phone, and the phone memory have 180MB free, not counting the SD card.

Just today, the phone rebooted itself - and I wasn't even using it !!!!

[#4]

I just asked because there is software "out there" that performs auto soft resets.

Do you have enough power on the battery. If the battery power becomes very low this can happen.

I would first of all perform a clean reset and install the latest update if it is possible.