LAX, LA's airport caused big trouble for 17,000 passengers last week, due to computer malfunction. What happened ? One single computer inside the customs office crashed. The networkcard of that computer caused a domino effect on other systems in it's range.

U.S. Customs officials say the card - - which allows computers to connect to a local area network - experienced a partial failure around 12:50 p.m. Saturday that had a domino effect with other computer network cards.(CBS)

After the computer came backup one day later, it experienced an outage again that lasted for 80 minutes. This time it was due to power supply failures.

It seems to me this is due to poor design. When you design your network, you should think about these scenarios, as a lot of things can easily be prevented.