W2K PC looses thumbnails in floder view

A Windows 2000 Professional laptop has lost it’s ability to display thumbnails of image files when an image file is selected in any folder. It will display a thumbnail under the file information in the folder view for bitmap images, but cannot do the same for JPEG files. I have check the file association for JPEG files and it seems correct with IE set to open JPEG format files. I have also tried change the folder view option, without any success. If anybody knows what setting was changed, I would appreciate a reply.