|(jargon)||heisenbug - /hi:'zen-buhg/ (From Heisenberg's Uncertainty
Principle in quantum physics) A bug that disappears or alters
its behaviour when one attempts to probe or isolate it. (This
usage is not even particularly fanciful; the use of a debugger
sometimes alters a program's operating environment
significantly enough that buggy code, such as that which
relies on the values of uninitialised memory, behaves quite
In C, nine out of ten heisenbugs result from uninitialised auto variables, fandango on core phenomena (especially lossage related to corruption of the malloc arena) or errors that smash the stack.
Opposite: Bohr bug. See also mandelbug, schroedinbug.