To resolve this problem, you must force Windows Live Photo Gallery to regenerate the database. To do this, follow the steps for your operating system:
1 - Close Windows Live Photo Gallery.
2 - Click Start
3 - type (or copy and paste) %userprofile%\AppData\Local\Microsoft\Windows Live Photo Gallery in the Start Search box, and then press ENTER.
4 - Right-click Pictures.pd4, and then select Rename.
5 - Change the name of file to OLD_Pictures.pd4
6 - Start Windows Live Photo Gallery.
Note Windows Live Photo Gallery will re-create the database based on the metadata and information that is stored in your media files. Any metadata that is not written back to a media file will be lost. For example, the metadata could be lost because a media file was locked or read-only.
Alan - I tried this myself to ensure it works correctly.. IF it doesn't work on your machine then try substituting line 3 above for %userprofile%\AppData\Local\Microsoft\Windows Photo Gallery