Ja som len googlil windows7 wallpaper problem a napr. http://answers.microsoft.com/en-us/windows/forum/w indows_7-desktop/unable-to-change-background-windo ws-7-home-premium/8d350714-8b71-4d29-b8fe-0f67707c e36e
t.j. kuknut co je v %USERPROFILE%\AppData\Roaming\Microsoft\Windows\Th emes\ a pripadne zrusit obsah apod prip. over ci ma vobec prava na zapis tam.

inac skontroluj ci to neni zavirene, ja totiz neverim ze to vzniklo vytrhnutim USb sticky, ale skor bol ten USB stick nejak zavireny apod.