I have a problem that occurs seemingly randomly on my Macbook Pro, 13" 2010, running 10.7. The background on the secondary screen (which is actually the laptop screen itself, the primary screen is a Cinema Display) will go gray. I can still use the screen, it shows everything but the background image. I can even drag desktop icons to that screen. Changing the wallpaper does nothing.
Most of the users in this discussion seem to be having a similar issue.
I tried "killAll Finder" to see if I could get it to reset itself (it will fix itself after reboot). Apparently, that process is not in charge of the background image, because the background stays while the desktop itself (file icons on the desktop) disappears while Finder is restarting.
So, is there a process I can try restarting that will reset the wallpaper state?