How to fix Windows Defender error 577 in Windows 10
Windows Defender is an antivirus and anti-spyware utility that comes with Windows OS. In Windows 7 and earlier versions of Windows it used to have anti-spyware functions only and could run alongside third-party AV’s, but in Windows 8 it has become a full-fledged antivirus. When another AV is installed, Defender gets turned off so the two won’t impede each other’s work. One other reason for Defender getting shut off is malware damaging some related files or changing Registry settings.