heisenbug
/hi:'zen-buhg/ [from Heisenberg's Uncertainty
Principle in quantum physics] n. A bug that disappears or alters
its behavior 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
uninitialized memory, behaves quite differently.) Antonym of
Bohr bug; see also mandelbug, schroedinbug. In C,
nine out of ten heisenbugs result from uninitialized auto
variables, fandango on core phenomena (esp. lossage related
to corruption of the malloc arena) or errors that smash the stack.
