Yesterday I updated from 14.10 to 15.04. Upon restarting I was greeted by a lovely change to my desktop background.
I was previously using a default background. I figured it just needed to be refreshed so I changed the wallpaper to another image. However instead of the image I still just got what looks to be a garbled mess of memory. It was however slightly different for every image I tried.
On the login screen the background image appears correctly.
Does anybody know why this is happening or what I might be able to do to fix it?