Had several discussions with IB Technical Support about the TWS freezing. After months of trouble shooting, the technician correlated the time of occurrence on my workstation to server loads at IB. (Wasn't easy for him to do that). He suggested it could be IB server rebalancing issues. As servers max out by users, users may be transferred to other servers. However, there may be a lag in the transfers and results in slower response or (gasp) server freezes that appear as workstation freezes. Here is the manual fix for TWS users: [Q] How to reset TWS connections? [A] Ctrl-Alt-F resets the market data connections Ctrl-Alt-R resets the account server connection Restarting the TWS will accomplish the same. Rebooting the workstation will accomplish the same. Of course, it is best to make sure one's workstation is optimized and apply the above answers as needed.