wallpaper switcher not working and black background

Today my wallpaper has disappeared and I am left with a black background. How do i fix this?

I think it was Nemo file manager causing the problem since I installed that to replace the latest atrocity of Nautilus. I have disabled the Nemo autostart and let Nautilus handle the desktop drawing and the background came back.

http://ubuntuforums.org/showthread.php?t=2118617

Fix mentioned there