PC Mag has published the first part of their guide on making Windows Vista a better operating system. In the first edition they focus on fixing Windows Explorer:
Windows Explorer has a nifty thumbnail display that shows iconic previews of your pictures, videos, PDFs, and even MP3 album folders. But accompanying this eye candy is Explorer's baffling inability to determine the type of files in a given folder, which leads to the wrong view almost every time. This is why you may see spreadsheet files as thumbnails and JPEG images in the Details view, and why changing the view doesn't ever seem to stick.
The root of the problem is templates, Vista's cumbersome method of saving different view settings for different types of files. You can right-click a folder, select Properties, and then click the Customize tab to choose the template to use for that folder (Pictures, Documents, and so on), but that alone won't stop Explorer from ignoring your preference and picking whichever template it wants..