This policy setting allows user to suppress reboot notifications in UI only mode (for cases where UI cant be in lockdown mode). If you enable this setting AM UI wont show reboot notifications. Counter Measure: Configure this setting depending on your organizations requirements. Potential Impact: Users will be able to see reboot notifications in the AM UI. Fix: (1) GPO: Computer Configuration\Administrative Templates\Windows Components\Windows Defender\Client Interface\Suppresses reboot notifications (2) REG: HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows Defender\UX Configuration!SuppressRebootNotification