I upgraded this blog to WordPress 2.5 today, and installed a new copy of WordPress on a subdomain too. Both these actions were carried out using cPanel & Fantastico.
When I logged into the backend of the new subdomain there were no images – including no buttons on the rich-text editor (TinyMCE) and no WordPress logo on the login screen. I later noticed there were also background images missing on the public part of the new blog. When I right clicked “View background image” on the missing image, it took me to an HTTP 403 (Forbidden) meaning there was a permissions problem. The strange thing was the problem didn’t occur in the nerd. backend.
And the solution…? In this instance it was because I’d enabled hotlink protection in my server to stop other people using images stored at steveferson.com on their sites, because this eats up precious bandwidth. When I created this new subdomain, I had forgotten about the hotlink protection and so hadn’t added it to the list of sites allowed to link to images at SteveFerson.com. When I added it everything went back to working as expected.