Source : Free On-Line Dictionary of Computing

Cray instability
     
        A shortcoming of a program or {algorithm} that manifests
        itself only when a large problem is being run on a powerful
        machine such as a {Cray}.  Generally more subtle than {bug}s
        that can be detected in smaller problems running on a
        {workstation} or {minicomputer}.
     
        [{Jargon File}]
     
        (1994-10-13)