Strangers' gmail address superimposed on all Firefox screens
Hi. Today, I noticed an unknown gmail address is superimposed on every Firefox screen & site I visit. It is locked in position as I scroll.
I've refreshed Firefox, opened it in Safe Mode. Quit & restarted Firefox & still the strangers' gmail address remains in place, even when opening a Private Window.
Is "email@example.com" known to anyone? Have I been hacked? What can & should I do to get rid of this weird thing? Thanks.
Here's a screen capture. (I added the red oval.)