Windows XP has a neat feature for graphic and video files that creates a “thumbnail” of the image or first frame of the video and makes it into an oversized icon for the file. There are two ways that Explorer can do this, it can create them fresh each time you access the folder or it can load them from a thumbnail cache. The thumbnail caches on systems with a large number of image and video files can become staggeringly large. To disable the Thumbnail Cache, browse to HKEY_CURRENT_USER \ Software \ Microsoft \ Windows \ CurrentVersion \ Explorer \ Advanced and find the DWORD “DisableThumbnailCache”. You may need to create this key. A setting of 1 is recommended for systems where the number of graphic and video files is large, and a setting of 0 is recommended for systems not concerned about hard drive space, as loading the files from the cache is significantly quicker than creating them from scratch each time a folder is accessed.
Here what u have to do:
Got start > run And type regedit
Then Go to
[HKEY_CURRENT_USER \ Software \ Microsoft \ Windows \ CurrentVersion \ Explorer \ Advanced