Windows Vista will not display the thumbnail images of WMF files, like it did in XP. This is due to the exploit that was found that allowed malicious code to be embedded in WMF files. When those files are previewed, or opened, the code would run on the system.
There was a security update released to block this issue in Windows XP. Windows Vista has this update embedded into it. Due to the way Vista now previews the thumbnails of images, this embedded update will block the viewing of WMF thumbnails. There is no way to turn this off.
Also, any program that uses the Vista component to view the thumbnails will run into the same issue. For example, Microsoft Office programs are no longer able to view the thumbnails for WMF files when trying to insert them. The images will still display in the documents once inserted. It is only the thumbnails that will not be displayed.
To view the thumbnails, you need to use the Portfolio Browser software and open the catalog files on the disc. The catalog files have proprietary thumbnail image format, so it will not run into this problem.
There are other programs that will run on Vista to generate a preview of the WMF images. Essentially, those programs convert the images into the program’s own propriety thumbnail format and display those instead. You may find one of these other programs will work for you instead of the Windows Explorer. We cannot provide support for these other programs.