Editing Crash (computing) (section)

==Application crashes==
[[Image:Computer crash airport.jpg|thumb|A display at [[Frankfurt Airport]] running a program under [[Windows XP]] that has crashed due to a [[Segmentation fault|memory read access violation]]]]

An [[Application software|application]] typically crashes when it performs an operation that is not allowed by the operating system. The operating system then triggers an [[exception handling|exception]] or [[Signal (IPC)|signal]] in the application. Unix applications traditionally responded to the signal by [[Core dump|dumping core]]. Most Windows and Unix [[Graphical user interface|GUI]] applications respond by displaying a dialogue box (such as the one shown in the accompanying image on the right) with the option to attach a [[debugger]] if one is installed. Some applications attempt to recover from the error and continue running instead of [[exit (system call)|exiting]].

An application can also contain [[code]] to crash{{efn|In [[OS/360 and successors]] the application normally uses an [[ABEND]] macro with a user completion code.}} after detecting a severe error.

Typical errors that result in application crashes include:
*attempting to read or write memory that is not allocated for reading or writing by that application (e.g., [[segmentation fault]], x86-specific [[general protection fault]])
*attempting to execute privileged or invalid instructions
*attempting to perform I/O operations on [[computer hardware|hardware]] devices to which it does not have permission to access
*passing invalid arguments to system calls
*attempting to access other system resources to which the application does not have permission to access
*attempting to execute machine instructions with bad arguments (depending on CPU architecture): [[Division by zero|divide by zero]], operations on [[denormal number]] or [[NaN]] (not a number) values, memory access to [[Bus error|unaligned addresses]], etc.

===Crash to desktop===
A "crash to desktop" (CTD) is said to occur when a [[computer program|program]] (commonly a [[video game]]) unexpectedly quits, abruptly taking the user back to the [[desktop metaphor|desktop]]. Usually, the term is applied only to crashes where no error is displayed, hence all the user sees as a result of the crash is the desktop. Many times there is no apparent action that causes a crash to desktop. During normal function, the program may [[Hang (computing)|freeze]] for a shorter period of time, and then close by itself. Also during normal function, the program may become a [[Black Screen of Death|black screen]] and repeatedly play the last few seconds of [[sound]] (depending on the size of the audio [[data buffer|buffer]]) that was being played before it crashes to desktop. Other times it may appear to be [[Event-driven programming|trigger]]ed by a certain action, such as loading an area.

CTD bugs are considered particularly problematic for users. Since they frequently display no error message, it can be very difficult to track down the source of the problem, especially if the times they occur and the actions taking place right before the crash do not appear to have any pattern or common ground. One way to track down the source of the problem for games is to run them in windowed-mode. Certain operating system versions may feature one or more tools to help track down causes of CTD problems.

Some computer programs such as ''[[StepMania]]'' and BBC's ''[[Bamzooki]]'' also crash to desktop if in full-screen, but display the error in a separate window when the user has returned to the desktop.