Hi Photofan,
Do you have another user account that you can try Windows Photo Gallery and see if you get the same error message? If you do try it with another account and don't get the message try going through the following steps and see if it resolves your issue.
1. Click the Start orb
2. Type folder options in the Start Search box, and click the Folder Options program
3. Select the View tab
4. In the Advanced Settings window, underneath Hidden files and folders, select Show hidden files and folders
5. Click OK
6. Navigate to the following folder ( %user% is the name of the account having the problem):
C:\Users%user%\AppData\Local\Microsoft\Windows Photo Gallery
7. Copy any files in here to another location as a back up and then delete them from the Windows Photo Gallery directory
Once the files are deleted, try to start Windows Photo Gallery.
After that go back in to folder options and select Do not show hidden files and folders
Let us know if you have any other problems. Thank you
Shane
Microsoft Answers Support Engineer
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