It looks like it is a notification you turned on on a certain site, it is not a real virus warning. See Web Push notifications in Firefox for information how to revoke the permissions for that site (look at your screenshot to the adres noted after via )

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Tim Maks , SUMO volunteer Please mark the answer with the right solution with "Solves the problem" to help other users with the same issue

I then re- installed Firefox, , it picked up my data and the virus message popped up again. I immediately uninstalled it again. I use REVO to uninstall, which scans for left overs, which I delete as well. Now I HAVE TO ASSUME that Revo is NOT clearing ALL FIREFOX files/data off my PC. Please advise where it is and how I can delete it completely, which is causing the messages to pop up again as soon as i install Firefox.

Normally, it is desirable to preserve your browser data (under %APPDATA%\Mozilla\Firefox) when uninstalling/reinstalling program files. If there is a problem in your profile, typically is it related to settings or add-ons, and you can use the Refresh feature as a shortcut to diagnosing/cleaning those. See: Refresh Firefox - reset add-ons and settings.