Harry,
I've had the same problem since upgrading to the newest version. I go to enter a limit order at a specified price and then the trade executes immediately not at the price i entered. It's weird. Sometimes I'll have a limit price loaded up, and when I right-click just before transmitting, I'll notice that my limit price has defaulted back to some other price. Another thing I noticed is that the very first trading page tab will not save with the title that I want. It keeps defaulting back to "untitled" after i reboot. I haven't called IB yet on these bugs, if that's what they are.