Are u hitting the 'power' button on the start menu to shut down vista? If so, that doesnt actually shut it down. It puts it into sleep as default, and I know some of the builds ive done on Vista have issues coming out of sleep and often crash. U can change the power button settings so it shuts down like on XP, or click on the arrow to the side of the restart? button and it will give u all the restart/hibernate/sleep/shutdown options to choose from.