A client computer is connected via a network to an anti-virus server and
polls the server for indication that an anti-virus needs to be
immediately downloaded from the anti-virus server. The client computer
disengages from the network, and re-establishes a link with only the
trusted anti-virus server. The anti-virus fix is installed, the client
computer re-booted, and the client computer is then allowed to reconnect
to the full network. If the client's primary operating system (OS) is
infected, a secondary OS in the client computer performs the anti-virus
download and execution. The disengagement from the network is performed
by applying a filter in a network interface card (NIC) driver by the
primary OS, the secondary OS, a service processor (SP), or by a virtual
machine manager (VMM), depending on which is available at the client
computer.