$Crash 
This is what happens when your computer goes wrong and freezes up. A crash can be caused by all sorts of problems with the software, but is normally because the computer has got itself into a terminal muddle or that the software you are using has bugs in. This means there is something wrong with it which the developer had not sorted out before it was released. When a PC crashes, the only way to get out of this is to switch off or reset (using the reset button or by pressing Ctrl-Alt-Del at the same time). Unfortunately, you will lose any new work you've keyed in since you last saved your work, so make sure that you save your work regularly.