I've had my MacBook for 2 years now, and I have never run into this issue before. A friend of mine sent me a JPG file with a white background. In my email, the thumbnail of the attachment showed that it had a white background. However, when I downloaded the attachment and opened it, it had a black background. I had her re-send the image, and the same thing happened. She told me the background was supposed to be white.

Frustrated, I took the photo into photoshop and changed the background to white myself, and uploaded it onto our facebook page. It showed as white for me, but black for her!

Any idea what could possibly be going on here? She was using her iPad to view everything...