Whenever I start up my Macbook pro with retina display, the wallpaper always reverts back to the default wallpaper apple sets (the galaxy or whatever it is). So, every time I have to go to settings and choose the wallpaper I set for it to show up. This happens to the wallpapers I saved and the ones that come with the computer. Does anyone know how to fix this? It is starting to get really annoying for me.