Abstract: The present invention provides a portable and secure computer operating system, and applications that can be used securely on virtually any computer system regardless of its security state (i.e., regardless of the presence of computer viruses, Trojan code, keylogging software, or any other malicious mobile code that may exist on host computer system). The present invention is embodied within three (3) components including 1) the client desktop or server software, 2) the appliance-based management server, and 3) the media (i.e., including but not limited to USB thumb drive or CDROM) on which the client desktop or server software is installed.