Opening new desktop sometimes shows me the old wallpaper
Sometimes when i change my desktop wallpaper to new one, and when i add new desktop it shows the old wallpaper... and sometimes when i change my wallpaper and restart my mac my old wallpaper shows up, when i try to change "Desktop & Screen Saver" in the preview it shoes the new one but it gives me the old one
OS X Mountain Lion (10.8.3)