if you read the papers or the public SEC reports, yes it was some vague "computer glitch".
you want to guess at what actually happened?
you (the human) put in an order. one order. your effort, after thoughtful consideration takes perhaps a minute to make the decision and clickety-click away we go.
One minute? Slow human! Compare:
That day (and similarly, the more recent 'flash crash', but with different actors) HFT computers more or less went to war with each other (Credit Suisse's Blast algo is one of the more well-known culprits), and they started sending in THOUSANDS and THOUSANDS of orders per second, along with THOUSANDS and THOUSANDS of cancels for those orders mixed in.
They DoS'd the private market-participant <-> brokers' WAN links.
They basically blew up the pipes (nine hundred pounds of flour won't fit in a five pound bag), and the market centers (NASDAQ first) all pushed the stop button so they could figure out what to do next.
Some "computer glitch".
ha.
R.
