a Shot i took has over saturated skin tones. so I toned it down in lightroom and exported it. But I set the original picture (with the wrong skin tone) as desktop background once. Ever since then I am not able to switch the background to the correct version! I deleted the original, exported the corrected version, pointed it to that picture and bang, the old saturated picture showed up. Must be a weird cache setting in Windoes 8..... so strange