When I use Windows Explorer in thumbnail or filmstrip mode, any file that is not a folder appears with a checkmark centered and between the thumbnail and filename. The checkmark looks just like the one used by McAfee. The lower left quarter of the thumbnail is also hidden by "white space". This makes viewing photos/images almost impossible. I have uninstalled McAfee and still have the same problem, so of course tech support says it's not their problem, call MS or ISP. Yeah, right, I don't think so!
If the issue is not seen after removing McAfee then its unlikely to be a McAfee issue but try this
and if that does not work there is a chance that the images do not have a program for it to view.. are all of them JPEG or gif ? Do you have Adobe or some software that runs as an image viewer? perhaps re-configuring it to accept the file type might help.
Yes as Vinod has pointed out it could be a problem with the image previewer or the default picture previewer has been disconnected. But before we could conclude it would be great if we can have a screen shot of the same.