You could try this fix
http://www.pcmag.com/article2/0,1895,915185,00.asp
As an aside: I've never been too fond of Windows's thumbnails. I prefer dedicated image browsers. I personally use xnview (
http://www.xnview.com - freeware). I recommend it because it's very fast and compact (not clunky at all). More people use irfanview though.