The hacker discovered that if you place several withdrawals all in practically the same instant, they will get processed at more or less the same time. This will result in a negative balance, but valid insertions into the database, which then get picked up by the withdrawal daemon. ~ D'Agosta

If I did not make this adjustment, people would most likely withdraw all their BTC as soon as possible in order to make sure they weren't left in that remaining 12.3%.