A program is using Microsoft’s sounds without permission.

LMMS is not “stealing” Microsoft’s sounds. Windows provides a set of built‑in system sounds and APIs that applications can legitimately use. Applications are expected to use these system sounds where appropriate rather than bundling their own copies.

From the Windows UX sound guidelines:

Programs are encouraged to use the built‑in Windows system sounds whenever appropriate instead of shipping their own sound files.
System sounds are configured and controlled centrally through Windows (for example, via the Sound control panel and volume mixer), and applications typically play them through standard APIs.

What is likely happening in this scenario is:

LMMS is playing standard Windows system notification sounds via the Windows audio APIs.
The “muted” state being changed is probably only for a specific output (for example, the Windows “System Sounds” session or the LMMS session in the volume mixer). If LMMS is using or routing audio differently, it may still play sounds even when a particular session is muted.

This behavior does not indicate that LMMS has copied or embedded Microsoft’s sound files without permission. It indicates that LMMS is using the Windows system sound events as designed.

If the goal is to stop hearing those sounds entirely, use Windows’ sound settings to disable or change the system sounds:

Open Change system sounds.
In the Sound dialog, under Program Events, select the relevant event(s).
Set Sounds to No Sounds for those events.

This prevents any application that relies on Windows system sounds from playing those particular sounds.

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