Had similar situation about 4 years ago with InstaQuote. I had a pair and market starts selling off, my short position's been closed during heavy selling. Called broker was told short is closed. I close my long and call instaquote, they do a search and say that order has been send from my computer. I take a loss for the day and start fresh next day.
You don't place a stop in case something like this happens? That way if a crash happens and your stop gets gunned before you get the computer back up then you are out of the market.