Abstract: A method for inspecting a host computer using a USB device, wherein the USB device is selectively operable in a mass storage mode and in a computing mode. The method comprises booting an inspection operating system on the host computer from the USB device, when the USB device is operated in the mass storage mode, the inspection operating system providing one or more inspection functions for inspecting the host computer, switching the USB device from the mass storage mode to the computing mode, and inspecting the host computer using the one or more inspection functions of the inspection operating system, the one or more inspection functions being controlled from the USB device operated in the computing mode.