PC keeps turning off display or going to hibernate or even shutting down randomly.

Specs:

No overclocking has been done, no under or over volts and no XMP

DDR4 12 GB

i5-12400F

GTX 1650

Windows 11-Pro

What I've tried and has failed:

Ran windows memory diagnostics.

Reinstalled Windows.

Checked Event viewer.

Replaced thermal paste. (in case it was overheating)

Exactly what's happening:

The computer works normally for some time. While I'm using Firefox, the bookmarks tab randomly opens once or twice. Sometimes this doesn't happen, but Outlook opens up once or twice. Then one of 2 things happen, it either sort of hibernates or sometimes shows shutting down and shuts down. I found a temporary solution to this which was turning on virtual cam in obs which forced the computer to disallow shutting off. This all started when I once plugged in a SATA SSD which I had bought from an offline store, it was used (I didn't know) and had viruses from the previous owner. When the pc didn't turn on properly, I removed the SSD and returned it to the shop, followed with a quick windows reinstall. Weirdly enough, while I play Valorant, this stuff doesn't happen.

Please try to help, I don't have money to test another CPU or motherboard or PSU.