I don't see how you could say that the computer problem fueled the plunge. My understanding of the events is that the only problem was with the system that calculated the Dow Jones Industrial Average Index (the number that is around 12,200). There wasn't a backup or delay in execution of trades or anything like that. The decline was real, but it was spread out over an hour instead of the 2 minutes reflected by the DJIA.

Traders still bought and sold stocks at their real value in real time. The calculation of the sum of their activity was the only thing delayed.