c.1400, crasschen "break in pieces;" with no identifiable ancestors or relatives it probably is imitative. Computing sense is 1973, which makes it one of the earliest computer jargon words. Meaning "break into a party, etc." is 1922. Slang meaning "to sleep" dates from 1943; especially from 1965. Related: Crashed; crashing.
1570s, from crash (v.); sense of "financial collapse" is from 1817, "collision" is from 1910; references to falling of airplanes are from World War I.
A person who attends a party or event uninvited: ruined by crashers