Hello. So i have an Windows 10 Pro.

Few days ago after i finished testing my ram in memtest86 ( bootable from USB ) , i change boot in UEFI BIOS from USB to SSD.
After this Windows 10 was showing at 1 boot Automatic Repair.
When starting Windows 10 boot loader starts by "preparing automatic repair" and diagnosing pc.
Then after this i get screen with Automatic Repair couldnt repair your pc.
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And the interesting is that if I restart Windows (after procedure mentioned earlier) it will boot normally. This startup problem was occured only when starting system again after shutdown or restarted pc from windows.So i was needed 2 boots to boot properly to windows. After screen with Automatic Repair couldnt repair your pc i was able to boot Windows 10 properly.
So i formatted disk and all is fine after format ,and windows 10 booting fine.
But i want to know why it happened earlier? That was still hardware issue? Thx for opinion. Somebody said that can be caused by bad ram or other hardware.

Also :

On my old laptop with Windows 10 Pro i made the same operation, i change boot from USB to HDD and on first boot Windows 10 shows Automatic Repair. But it happened once and i cant reproduce. No format was needed.
Weird that pc was needed to be formatted, when on laptop not, because Automatic repair on laptop happened once after changing boot in bios from USB to HDD and no more happened on next Windows 10 Pro boots.

Any ideas? Why on pc format was needed when on laptop not?

Pc :
2x8gb 1600mhz Hyperx DDR3
Asus Sabertooth Z97 Mark 2 UEFI

Laptop is old with 2gb ram and old standard bios ( no Uefi )