demented
     adj : affected with madness or insanity; "a man who had gone mad"
           [syn: {brainsick}, {crazy}, {distracted}, {disturbed},
           {mad}, {sick}, {unbalanced}, {unhinged}]
Source: WordNet® 2.0

demented adj. Yet another term of disgust used to describe a
   malfunctioning program. The connotation in this case is that the program
   works as designed, but the design is bad. Said, for example, of a
   program that generates large numbers of meaningless error messages,
   implying that it is on the brink of imminent collapse. Compare {wonky},
   {brain-damaged}, {bozotic}.


Source: The Jargon File