Unable to open Windows Photo Gallery

I found this error when trying to double-click my images. The error says:

“Error loading C:Program Files (x86)Windows Photo GalleryPhotoViewer.dll
C:Program Files (x86)Windows Photo GalleryPhotoViewer.dll is not a valid Win32 application.”
I'm using Windows Vista Home Premium OS 64-bit Service Pack 1. I have checked my computer for possible viruses. Then I also tried System Restore and use the system file checker and found this:

Can anyone help me in resolving this?
Thanks.
