I am a program trader. I shorted around 300 stocks of totally 4.5 million dollars. when I decided to close those positions, IB refused to take my order. All the liquidating orders were in the status "acknowledged but not transmitted". Until One hour later, my order started to take effective. This is very horrible today since the nasdaq kept going up. The stupidity of IB cost me 50K. later on, I received a message from IB "over excessive order submission, and my account is flagged". On Tuesday this week, I had the same problem but that time I did not receive IB message about the excessive submission warning. this problem occurred a number of times when there were too many positions in my account. I wonder any one came across the same problem.