WinMute is an Open Source utility for auto-muting your PCs volume when the lock screen or screensaver are running.

Designed to be a simple solution allowing you to mute sounds from your PC when specific criteria are met. WinMute ensures that whenever you lock your screen or your screensaver starts, WinMute will automatically mute your machine's volume. It will also unmute it when you unlock or disengage the screensaver.

WinMute is simple to configure and set up for any skill level of user. And if you need to temporarily disable it you can by right-clicking on the taskbar notification icon and uncheck the Mute on Workstationlock / Mute on Screensaver start menu items.