One aspect of trading electronically is that you better make sure your algorithms are correct, otherwise you are going to make stupid trades and suffer losses. Knight (NYSE: KCG) is the victim of their own electronic infrastructure, taking a 22% hit.
During the flash crash a bunch of trades were busted, but my personal opinion is that the only way to prevent these sorts of things happening is by depriving those that made the errant orders of their capital. Perhaps it will give a bit more incentive toward those that actually program their systems correctly, or heaven forbid, give it a little bit of human manual intervention before sending a billion-dollar order that has 10 minutes to get rammed through the markets.