Microsoft's September security update for Windows 11, KB5124008, is causing audio issues with USB audio devices, including unresponsive sound controls and lack of audio output. The problems are linked to USB Audio Class 1.0 devices and do not affect built-in motherboard audio codecs or wireless headsets. Users may see an error message “This device cannot start (Code 10)” in Device Manager logs. Microsoft is working on a fix, and users can temporarily switch to stereo settings for relief. Additionally, the update is causing gameplay disruptions, crashes, and other bugs, prompting users to report issues to Microsoft and consider pausing updates.