Well I've been chasing this problem for about a year. Things I have done. 1) reinstalled firefox 2)reinstalled windows 3)attempt to remove the ImportEnterpriseRoots flag via Regedit. (Mozilla does not even appear in in the policies folder) I Suspect this has something to do with having logged into my firefox account on a shared work computer, and the sysadmins subsequently removing the ability to use personal firefox accounts on these computers, to the point of not even being able to logout of the account.

It just keeps coming back. I only have MS Defender for security so I don't think its security software causing it, and I do not believe a virus/rootkit would survive several formats and reinstalls.