My screen has gone pixilated with tiny 1mm squares. The Mac is otherwise working. Help!!

Hi BaldoyleDub,

Welcome to Apple Support Communities. You're having some issues with your Mac display resolution which looks pixelated. Right?

If the screenshot you provided appears pixelated on your end, it doesn't show up that way in your post. One step that may help with screen resolution issues is resetting your NVRAM. Try the steps in Reset NVRAM or PRAM on your Mac, then see if the same issue continues.

Take care.