A fatal system error is a condition that occurs in a computer operating system that causes it to cease functioning. Both Windows®- and Unix®-based operating systems are designed to shut down in the case of a fatal system error and restart in an attempt to clear the problem and any software corruption from memory. The problem has been given the colloquial name on Windows® as "the blue screen of death," because, when a fatal system error occurs in a Windows® environment, a blue screen is displayed, often with scrolling text, which is a crash dump of the contents of memory into a file. This information can later be used to diagnose the cause of the error. On the latest computer systems, the blue screen of death no longer appears, as they are immediately set to restart if there is a system crash, primarily because the crash dump information is only of value to a programmer familiar with the coding of the operating system itself.
Modern computer operating systems are constantly running through a process of error checking while they work and correcting for errors behind the scenes of which personal computer (PC) users are rarely aware. Occasionally, however, a condition arises due to hardware failure, programming code that has failed, or processing errors in software running in memory, which a operating system cannot resolve automatically. The most common cause of a fatal system error is badly-coded software that is in some manner incompatible with the operating system it is running on.
One of the most frustrating drawbacks to encountering a fatal system error, also known as a stop error or system crash, is that everything the user was currently working on on the PC and was being processed in random access memory (RAM) will be lost. Since RAM memory loses its data storage when the system aborts and shuts down, files currently stored there cannot be recovered after a crash. If a computer or software program is designed to save work in progress periodically, such as a word processor set to save a document every ten minutes as it is worked on, this loss of data can often be avoided, as the file is being saved to the computer hard drive, not to short-term RAM memory.
Computer errors that cause a system to crash were quite common in the early days of personal computer systems and software development in the 1980s and early 1990s, but have since become rather rare. When a fatal system error occurs on a new computer system, the most likely cause is a new software program that was recently installed, or a driver for a new hardware device recently plugged into the computer. These types of crashes can be avoided by simply uninstalling the device or software.
Kernel error or kernel panic are other early computer programming terms for a fatal system error. A kernel is the core of a computer operating system that interacts with hardware, software, and shells, which are parts of the operating system that respond to user input and commands. The operating system loads the kernel first upon booting up, and it stays loaded in memory as long as the system receives power, as the computer cannot function without it. Because of its essential nature, it is stored in a protected area of RAM memory that cannot be overwritten by other software while the computer is in use, and, when a computer suffers a fatal system error, it means that this kernel of the operating system itself has actually become corrupted and failed to function properly.