Have you tried opening the image in a decent photo editor?
Try downloading a free trial of Corel Paint Shop Pro Photo and see if that does the trick.
paint can not open some types of images. So use a decent program.
If that still doesn't work it could be corupt but i don't think so if you can see the thumb...
Download Paint Shop Pro here
http://www.corel.com/servlet/Satelli...=1156169693940