ProtocolPort will damage your computer

Hi - my neighbour and I (not on same network or anything) but started getting "will damage your computer" pop-ups this afternoon. My current one says ProtocolPort but earlier it was something else. I suspect this may be adware but when I tried to download SpyHunter to remove it that did not work (it would not open). I don't know if this is related but last week I started getting "low memory" warnings. Have checked processing memory (there is plenty) as well as safari extensions (none). Does anyone have advice on how to stop these pop-ups/clean computer?

Thanks so much!