This is apparently a problem creating the DVD image file on your hard drive, which is necessary before the actual burning process. You should check in the program settings where PhotoStory is currently trying to create the image. (Access the program settings via the "P" key and find the different path settings under the directories tab.) Then check whether the location you're trying to write the image files to does actually have enough hard drive capacity left and permits write operations. Keep in mind that, depending on your slideshow size and whether you want to pack more than one slideshow on a single disc, you might need an entire DVD's capacity worth of free space on that hard drive partition. If that is not given, you should either free up space on the hard drive partition in question or change the path settings in the program to use a partition for the DVD image that does meet the requirements. The problem probably wouldn't have anything to do with the fact that you're running this on Windows Vista.