1. A method of diagnosing an operating system to malfunctions comprising the steps of: (A) storing a rule base pertinent to the particular operating system being diagnosed and being operable to reach one or more conclusions relative to the condition of said system and being comprised of a plurality of schema, each said schema being defined by a data structure having a plurality of slots in which particular attributes of the schema are stored; and (B) changing the contents of any predetermined slot of any predetermined other schema upon the occurrence of a predetermined event.