Repeated alerts & error reports appearing in right hand side of desktop

https://support.mozilla.org/en-US/kb/push-notifications-firefox#w_how-do-i-revoke-the-notifications-permission-for-a-specific-site Are these as small popups on bottom right corner of Firefox window?. If so then these are likely just web push notifications from sites you have allowed to send you notifications. Instead of useful information some may send you junk, spam or fake virus/trojan alerts etc. You can revoke these sites from sending you alerts as above KB article explains how.