''bug'' (Etymology)
In 1946, when Hopper was released from active duty, she joined the Harvard Faculty at the Computation Laboratory where she continued her work on the Mark II and Mark III. Operators traced an error in the Mark II to a moth trapped in a relay, coining the term bug. This bug was carefully removed and taped to the log book September 9th 1945. Hopper recounted the cause to be an actual insect stuck between the contacts of a relay in the logic mechanisms of the device. (wikipedia http://en.wikipedia.org/wiki/Computer_bug)

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The first known computer bug in uncompressed tar file (tape archive grin").

''Schroedinbug''
Schroedinbug is a term used in software programming to describe a computer bug that is not discovered, but shows up after somebody reads the source or uses the application in an unusual way. The program then stops working for everyone until the bug is fixed. Although this sounds rather impossible, some programs have carried latent schroedinbugs
The word schroedinbug comes from Schrödinger's cat thought experiment.

''Heisenbug''
Heisenbug is a term used in software programming to describe a computer bug that disappears or alters its characteristics when it is researched.

A common example are bugs that occur in a release-mode compile of a program but do not occur when researched under debug-mode, or some bugs caused by a race condition. The name is a pun on the physics term "Heisenberg Uncertainty principle", which is popularly believed to refer to the way observers affect the observed in quantum mechanics.

In an interview in ACM Queue vol. 2, no. 8 - November 2004 (http://acmqueue.com/modules.php?name=Content&pa=showpage&pid=233&page=5) Bruce Lindsay tells of being there when the term was first used and that it was created because Heisenberg said "the more closely you look at one thing, the less closely can you see something else."

''Bohr bug''
Bohr bug is a term used in software programming to describe a computer bug that, in contrast with heisenbugs, does not disappear or alter its characteristics when it is researched.

''Mandelbug''
Mandelbug (from fractal innovator Mandelbrot) is a computer bug that has causes that are so complex that its behavior appears chaotic. This word also implies that the speaker thinks it is a Bohr bug rather than a heisenbug.

It can be argued, according to same principle as the Turing test, that if there is no way for a judge to differentiate between a bug whose behavior appears chaotic and a bug whose behavior actually is chaotic, then there is no relevance in the distinction between Bohr bug and heisenbug, since there is no way to tell them apart.