I run Ubuntu 12.04 64bit on both my Laptop and my Desktop. I use the same desktop background (and same file format) on both computers. When I power up my laptop it brings up the user login screen, and the background picture shows behind the login prompt, then my icons appear when I log in.
This doesn't happen with my Desktop however. When I power up my desktop I get the login screen as normal, but I get the standard orange/purple background that is the default wallpaper.
How can I make the PC do the same as the laptop?