Are these small popups on bottom corner? if so then these may actually just be Web Push Notifications from one or more websites you have allowed to send you notifications from. Unfortunately some of the notifications from some sites can be fake virus and fake random Antivirus client alerts with fake McAfee alerts being the most common I see posted about here. You can revoke permissions for the sites. https://support.mozilla.org/en-US/kb/push-notifications-firefox https://support.mozilla.org/en-US/kb/push-notifications-firefox#w_how-do-i-revoke-web-push-permissions-for-a-specific-site Also this is a community support forum as nobody here or a Mozilla does direct support by email. To reply in this thread ( https://support.mozilla.org/en-US/questions/1464895) you scroll down to the '''Post a Reply''' box, type in reply and then click on '''Post Reply'''. Note the emails you get upon replies here are automated and are not for support.