新创建的模式窗口在Windows Vista中失去焦点并变得无法使用

Sometimes when I open a modal window in my Delphi application it takes a while to show up, then I notice that the application is kind of blocked, and what happened was that the modal form was open with ShowModal but wasn't displayed and the application became locked as if the Modal Window was in the first layer.Sometimes when I open a modal window in my Delp