To give another deviant a direct link to this FAQ answer, use the following code in your comment or forum post:
I'm a Firefox user and images have stopped loading in my browser. How can I fix this?
Please go to Options>Content and under the section entitled "Load Images automatically" click on the Exceptions button. Make sure that none of our servers are blocked. In addition make sure "Load Images" is checked.
Examples of servers: http://e.deviantart.net http://th05.deviantart.net http://fc02.deviantart.net