1. A computer system configured to monitor the execution of a target program intended to run on a target computer, said target computer having an instruction set, said computer system comprising: a processing unit; instruction emulation means for operating said processing unit to emulate instructions in said target program corresponding to said instruction set as if said instructions were running on said target computer; monitor means, coupled to said instruction emulation means, for emulating execution of said target program as if said target program were running on said target computer and for monitoring said emulated target program execution to detect a predetermined behavior by said target program; and means, coupled to said monitor means, for logging said predetermined behavior when detected.