Yes perhaps. You may be using R7 AMD onboard video. I discovered this problem only manifested after installing the catalyst drivers from AMD for that onboard chip set for 2 different machines, confirming the result.
Removing the catalyst drivers seems to fix the problem. That said I don't doubt there's a way to make the catalyst drivers work with Photo Gallery such that there is no corner missing problem. Also previous to removing the catalyst driver I was getting an occasional message that "Photo Gallery Stopped Working and has to shut down". If anyone discovers the catalyst setting that fixes this problem please let us know.
When I open an image in Windows Photo Gallery it is squished over to the left and side of the screen. The image is also in black & white with vertical lines going through it. I was having the same problem when I made youtube and other flash movies full screen. I found a fix for the youtube problem but I can't find a solution for Windows Photo Gallery. Can anyone help?