A friend who installed the Windows 7 beta was complaining about the shutdown screen. It tells you that an application is preventing shutdown, but it prevents you from interacting with the application to do something about it. Instead, you can either kill the application or cancel the shutdown, interact with the application, and then shutdown again. What idiot added this feature?
Vista does the same thing. Fortunately, I'm not too familiar with it because due to standby to RAM and hibernate I rarely shutdown or restart.