A corrupted mss32.dll or mss64.dll file causes this error.
or your motherboard manufacturer's support page to download the latest drivers. Adjust Audio Sample Rate
If mss.dll is missing entirely from your folder:
Whether you're revisiting a classic or encountering this on a modern setup, here is how to resolve the error. 1. Fix Audio Hardware Conflicts (The "Mic Hack")
When Call of Duty launches, it tries to turn on your microphone and speakers. Something is blocking the Miles Sound System from starting. Because the game cannot verify your audio setup, it refuses to load the multiplayer component to prevent crashes.