I have been getting this error since a couple weeks. I thought it would go away with new updates of TWS but it persists. I submit around 50-60 equity orders (buy/sell) using the "transmit page" option in the "order" menu... and not all make it through to the exchange and stay "unsubmitted" after I click OK in the error box, then I have to resubmit again, and again, and again. Until all orders are in. Any suggestions?