Prevent changing desktop background Prevents users from adding or changing the background design of the desktop. By default, users can use the Desktop Background page in the Personalization or Display Control Panel to add a background design (wallpaper) to their desktop. If you enable this setting, none of the Desktop Background settings can be changed by the user. To specify wallpaper for a group, use the 'Desktop Wallpaper' setting. Note: You must also enable the 'Desktop Wallpaper' setting to prevent users from changing the desktop wallpaper. Refer to KB article: Q327998 for more information. Also, see the 'Allow only bitmapped wallpaper' setting.

(1) GPO: User Configuration\Administrative Templates\Control Panel\Personalization!Prevent changing desktop background (2) REG: HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\ActiveDesktop!NoChangingWallPaper