Abstract
The complexity of information technology systems has increased to approximate that of biological organisms, with a similar unpredictability of behaviour. With several million lines of code, a modern computer operating system, still can only be compared in complexity to a bacterial genome. However, just as unpredictable mutations continuously arise in the 3000 million haploid base pairs of human code and cause much misery and disease, undiscovered errors lie buried in the accumulated machine code which make up our world. As in human genetics, the difficulty is often distinguishing the harmless polymorphisms from the dangerous or lethal mutations. Similarly there is uncertainty about the impact of errors in data-handling code, which make up the "Year 2000 Problem. Over the remaining months it is vital that critical systems are checked for year 2000 compliance so as to avoid potentially serious disruption.