Win 10 system encounters a solution that prompts that Windows Defender is closed: 1 Enter "Windows Defender" in the search bar of Start Menu to search; 2. Enter the group policy management template under computer configuration; 3 Find "Windows Defender" and double-click to open it; 4 Select "Enable". Note: If other antivirus software is installed and can keep the software running normally, it is not recommended to open Windows Defender (there may be conflicts).