1. A fault tolerant computer system comprising: a first processor system configured to run a first plurality of virtual machines; a second processor system configured to run a second plurality of virtual machines; a private network, the first processor system and the second processor system in communication via the private network; a business network, the first processor system and the second processor system in communication via the business network; and a system manager adapted to monitor operation of the first and second processor systems and the respective pluralities of virtual machines and to (i) migrate one or more of the respective virtual machines from the first processor system to the second processor system in response to an error in the first processor system, or (ii) migrate one or more of the respective virtual machines from the second processor system to the first processor system in response to an error in the second processor system.