This happens to lot of people. When you right click on an image you can see an option called “Block Images from |1.yimg.com” (www.yahoo.com).
Actually you may be going to send the link of the image to someone. But accidentally you have clicked on this option. The bad news is those images do not display you at the next time the same website loads. Too bad ahh ?
Here is how to unblock images of any web site on Mozilla Firefox.
Go to “Tools” and “Options”
Then refresh the page and images will appear consequently. Now you are done.