USBMUXD is a Mac OS X process that performs USB multiplexing when synchronizing iTunes music libraries with USB music devices like iPods & iPhones. It is not malicious. To stop these alerts, launch VirusBarrier X6, click the Privacy button at the top of the window, and click the Antispyware tab below. Once you have allowed USBMUXD at least once, it will appear in the left-hand column. Highlight USBMUXD in the list found in the left-hand column in this window. To the right, in the list, find Undefined port behavior and set it to Allow outgoing connections.