A fix has been provided by Microsoft for customers that have come across issues with Windows Live Photo Gallery in Windows 7. According to Microsoft, "Windows Live Photo Gallery freezes or does not start when you try to start it in Windows XP, Windows Vista, or Windows 7.
This issue occurs because a database is corrupted. This database is created by Windows Live Photo Gallery to track photos and videos."
An automatic fix is available from Microsoft through KB944221.
Microsoft has also detailed the steps to resolve the problem manually: