If I enable the thumbnails view in explorer and I apply an explorer background in XP, there is always one or two thumbnails that seem to be behind the background image. See the screen shot. This also happens to folders when in thumbnail view. Has anyone experienced this or found a way to prevent that from happening? The Zbthumbnail.info file is from my canon camera's picture browser, I deleted it and it made no difference. That file is only present in folders containing pictures I uploaded from my camera, and this problem seems to happen randomly in other places as well. So I do not think that's the cause.
Do you have Picasa installed? I think it might be doing something funky. I get the same thing on mine.
It's not that the thumbnail it's hiding behind the background, as much as that it's being made somewhat transparent by the system. Usually this is the system's way of letting you know that the file is marked as hidden when you have View hidden files enabled in Explorer.
I'm still not 100% sure on what causes this but I'm Picasa is my prime suspect.