You might have noticed that there is a hidden file called thumbs.db created in some folders. This file is automatically created within a folder when the thumbnails view is used to view that folder.
This is file is not a virus and many people take it so.
This file just contains information for windows, to display the thumbnail of a picture as the icon of that folder when the user switches to thumbnails view. If you find this file annoying then you are free to go ahead and delete it or disable its creation.