I was having some small problems in the Windows Explorers this last days ( and with all applications, since the explorer is used for every single file selection box in Windows apps): whenever I choosed the Thumbnail view thumbnails were not shown. And I work a lot with JPG pictures, so it was a pain not being able to preview them before copying or renaming. I think it was not working properly since the very first day, but some web pages I have read in the net blame on changing the image files asociation to another program ( I have asociated all image files to the great Irfanview , a great feeware program to view, convert and make simple modifications in computer image files).
There is a way to make Windows to display the thumbnails again... but not a very straightforward one: all pages I found require you to make manually changes in the System Registry. To speed up the thing, I created this small file that contains already the required changes in the System Registry. To make the fix, just download it and double click to insert the changes in the Registry.
I do not believe using this file could make any harm to your computer. But use it at your own risk. This is just a text file, just check the contents before executing it.