IE is a weird beast, and the fact is a lot of things go wrong and pop-up as errors in the TD that never should. I get error reports all the time that are simply "Permission denied", which is IE saying you can't access this thing right now. Or "XXX is null or not an object" or similar errors, where a property on an object just disappears. None of these should happen, but they do.
Because of the nature of the screen transitions, I tightly wrapped it in error handling code, so that should anything go wrong during a transition, the error should be caught and the transition aborted. In cases like these, the next screen should just appear instantly, like it does in previous versions, or like it does with transitions off.
The fact that you have transitions disabled seems strange, especially in light of the little blob in the middle of your screenshot. However, looking at the code, all movement from one screen to another starts out as a transition and simply jumps directly to the end of the transition if Screen Transitions are disabled. Furthermore, the transition setup code is less error checked. So it could be that the next screen is being setup and an error occurs in the setup code that isn't necessarily caught.
I'll have to add some more error handling code around the setup of the transition.