Does Windows Defender appear randomly on your PC and tells you not to turn your PC off OR do I have a virus on my PC

I've scanned for Malware and did not find anything I also run a scan and there was nothing.

Also I have Run netstat -ano and a window I don't see anything that appears t be a concern.

What action should I take when this happens again? It has happened 3-4 times over the past few weeks.

Thank you!