Recently my desktop wallpaper started disappearing. It comes on briefly at the end of boot up, then goes black. It will return at the moment I click on "Personalize" then "Desktop Background" -- just clicking brings it back, without choosing a picture. Then, after hibernating or sleeping, I lose it again. Having to keep manually restoring it is a pain, otherwise I have a blank screen. I do not use the sidebar feature, but it doesn't matter.