Today morning my PC suddenly rebooted after motherboard logo, but before windows logon screen. And it seems that it does this every time I shut down PC (start-power-shutdown) and then start it with power button. If I restart PC (start-power-restart) everything is fine and properly boots without problems. This PC is 3 months old and everything worked fine until this morning. I've made no changes to software or drivers for at least a week except windows defender auto updates. I've checked Windows Update and last updates were downloaded 1 December. Event Log logs two errors:
1. The previous system shutdown at [Time of shutdown] on [date] was unexpected.
2. The system has rebooted without cleanly shutting down first. This error could be caused if the system stopped responding, crashed, or lost power unexpectedly.
I've heard about fast startup problems of this kind and if I tried to disable this function and it helped, but I've never had problems with fast startup on my previous PC with HDD or this new with SSD, but it seems that they are suddenly appeared. What can cause this and how do I fix it without disabling fast startup?
Operating System: Microsoft Windows 10 Pro 1709 (OS Build 16299.98 - updated after problem occured)
CPU: AMD Ryzen 5 1600
Motherboard: MSI B350 PC Mate
GPU: Asus STRIX GTX 950
RAM: 8 GB DDR4 kingston memory at 2133 mhz
System Drive: Samsung SSD 850 EVO 250GB (250 GB, SATA-III)
Secondary Drive: WDC WD20EZRZ-00Z5HB0 (1863 GB)
PSU: XIGMATEK NRP-PC702 700W