Hi Sophie,
My name is Igor, it's a pleasure for me to help others and I'll try to help you.
Seems something is wrong with your system or hardware. Did you switch memory test to extended mode? If not, please do.
Repair system files by
DISM.exe /Online /Cleanup-Image /RestoreHealth
command from Windows Terminal (admin) environment.
For memory test result, please right-click Start, select Event Viewer, expand Windows at the left and select System journal. Then look for messages (events) from "Memory Diagnostics" source.