Previously when running the GNOME desktop (prior to 11.04 and the onset of Unity), I selected the desktop wallpaper that rotates through different images of the universe. I'm now using Xfce as my desktop with static wallpapers, but every so often the wallpaper changes to one of the images of the universe for about a second, then goes back to my static Xfce wallpaper.
How can I use the rotating wallpaper in Xfce instead of the static wallpaper?
If I cannot, how do I stop the different universe images from showing up for a second or so every so often?