The Webroot antivirus went berserk yesterday late afternoon, as it flagged core Windows system files as malicious, and even started moving some of the affected files into quarantine, trashing customer computers. The issue was eventually fixed, but many customers were left with hundreds or thousands of files moved to quarantine. The antivirus also started tagging Facebook as a phishing site, blocking access to the social network. Users took to the micro-blogging platform to show their discontent and trash the company.
Source: https://www.bleepingcomputer.com/news/security/webroot-antivirus-goes-off-the-rails-and-flags-windows-system-files-as-malicious/