From The Jargon File (version 4.4.7, 29 Dec 2003) :
crash
1. n. A sudden, usually drastic failure. Most often said of the system
(q.v., sense 1), esp. of magnetic disk drives (the term originally
described what happens when the air gap of a hard disk collapses). ?Three
lusers lost their files in last night's disk crash.? A disk crash that
involves the read/write heads dropping onto the surface of the disks and
scraping off the oxide may also be referred to as a head crash, whereas the
term system crash usually, though not always, implies that the operating
system or other software was at fault.
2. v. To fail suddenly. ?Has the system just crashed?? ?Something crashed
the OS!? See down. Also used transitively to indicate the cause of the
crash (usually a person or a program, or both). ?Those idiots playing
SPACEWAR crashed the system.?
3. vi. Sometimes said of people hitting the sack after a long hacking
run; see gronk out.