Abstract: Systems and methods are provided for utilizing virtual machines to protect computer systems. A first virtual machine may be initiated to execute a computer program. When the computer program attempts to access a computer file, a determination may be made of whether the first virtual machine is allowed access to the computer file. If access is allowed, the virtual machine may be permitted access to the computer file, and the computer program may thereafter access the computer file. A first (or “master”) virtual machine may additionally or alternatively cause initiation of a second (or “slave”) virtual machine to access untrusted computer files. Master virtual machines may be configured to communicate with and/or control slave virtual machines.