My screensaver froze while on a screensaver after i left upstairs for a few hours to watch tv.

This is only the second time my laptop froze on screensaver. I never set it to go go to hard sleep mode or power off fully after any set time on screensaver or inactivity.

I lost several unsaved images in paint.net a few minutes ago from this because my laptop did not respond to the key +ctrl + shift + b emergency command my phone showed on google.
I had to hard turn off my laptop by holding the power button down for several seconds. It was not work related images. But now i'm worried about this sneaking up on me again.
We have no repair places or laptop warranties since it was from costco and it is barely 2 years old. What causes this lock-up ? Everything is up to date.


Normally it waits for 30 minutes. But i'm putting my laptop on no screensaver at all for now.