To fix this in Vista: Goto "My Computer", right click on the drive the photos are stored and click "properties", then click on "Disk Cleanup". Put a Tick next to "Thumbnails" and then click "Clean up files". Go back to your folder where the photos are stored and press F5 on the keyboard, it should rebuild the thumbnails. If that doesn’t work then it simply doesn’t like the files and there isn’t much you can do.

For XP: In Windows explorer, press the alt key and it should being up the menu. Goto the tools menu and click "Folder Options". Click the "View Tab", and under advanced settings click on the "Show hidden files, folders, or drives" and also clear tick next to "Hide protected operating system files". Click OK, refresh the folder and then delete the thumbs.db file. Refrsh the folder again and it should rebuild the thumbnails.
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