Methods and devices for protecting computing devices against the effects of surreptitiously loaded machine language programs from a malware source. The user defines a pattern of disruption of the sequence of bytes. The user then installs legitimate programs to be run on a particular computing device by loading the original program onto the local hard drive and replacing the program by one to which the pattern of disruption has been applied. Using the user-defined disruption pattern, the computing device can define the transforms necessary to reverse the application of the disruptive pattern. As part of the process the operating system for the computing device is modified to apply transforms that reverse the disruption pattern when executing a program file loaded into RAM.