MAtt, Does the folder in question contain a thumbs.db file? If it does it may be corrupted so just right click the thumbs.db file and choose delete. A new thumbs.db file for that folder will be created after restart.
I do not know if this is an OS related issue or not. But I have a folder of digital photos. In thumbnail mode, If I look at the thumbnail, and compare it to the opened file, the pictures are not the same.. It seems that the file name no longer points to the correct file.File 1 opens up file 33 when I double click file 1. All files in this folder have the same result. Thumbnail looks good, opened photo is not the same photo.And only this 1 folder.
WINXP Pro. Photos from a Panasonic FZ20.