There is a hidden file named IconCache.DB that can become corrupted.
(Brink's site is down, so here's a quote on that

<quote>
Launch an elevated CMD window, ie Right click, Run as Administrator...
Shutdown Explorer Process from the Task Manager
In the CMD window go to C:\Users\<ProfileName>\AppData\Local
Do the following command: attrib -H IconCache.db
Do the following command: del IconCache.db
Do the following command: start explorer
This should rebuild the Icon Cache
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Mark L. Ferguson
..
"kosmos_corn88" <> wrote in message
news:186A1DC9-8C9B-441E-ACD8-...
> The wallpaper is not appearing at all on my desktop. Also the thumbnails
> are
> blank with nothing showing except for their filenames. This affected
> images,
> files, and folders. The thumbnails seemed to show the previews again after
> i
> cycled through the different views, but after i reopened windows explorer
> the
> thumbnails disappeared again. When i go to personalize to change the
> wallpaper form there it show blank thumbnails in most sections. in some
> sections it showed a fuzzy icon as a thumbnail. What could have happened
> and
> how do i fix it?