Pictures in Thumbnail are different to when I open them

Ok Guys, this is for a client of mine,

I have only been working this job for about a month, but Ive been working on computers since I was 10.

Here's my client's problem:
When I open Documents/pictures his pictures are all viewed as thumbnails.
When I open the thumbnail pic the picture is something completely different (one of the other pictures in the album)

Never experienced anything like this before and I need to know how to resolve this ASAP
Thanks

Try clearing the thumbnail cache first:

How to clear the thumbnail cache in Windows Vista?

And then setting the view option to details. You might also want to run the SFC - in a cmd prompt run sfc /scannow with a Vista DVD.