I searched for something similar but I can't seem to find someone else having this issue. Whenever I close the lid on my laptop and open it my ubuntu install loads up fine but my wallpaper just becomes black!? Unity loads up fine and is responsive, I'm typing this right after waking up my laptop, but my wallpaper is just black. The unity dash works fine everything is exactly as it should be but when I head to appearance and try to change my wallpaper back it just stays black. logging in/out doesn't change it in fact I have to do a full reboot to get it back to my wallpaper. I had this annoyance in 12.10 but logging in/out solved the issue so I lived with it but now in 13.04 that doesn't seem to work. Any ideas? Using nvidia 313.26 driver.