When I get the exception dialog (very similar to the bug logging dialog), if I just fill it in then it works OK (although Quit invariably just produces another exception and I have to use the Task Manager to kill AP).

However, if I move the exception dialog then everything hangs instantly (both the plan window and the exception dialog) and I can't even fill it out. I suspect you're generating an inval rect or something to redraw the plan window under the dialog but the app can't redraw as it's blocked by the original exception handler. Or something like that....