One of the profiles on my computer has a problem where some pictures (including thumbnails) do not show up on myspace when using firefox. Using konqueror is fine, and it is only that one profile. They use a custom skin so I don’t know if that has anything to do with it, and I am using the newest version of firefox.
Have you tried starting a new mozilla profile. In hidden /home/user
rename .mozilla to .mozilla_old
Start working with the new mozilla profile and see if it works. If it works. Add to it your custom features one at a time, see how it goes.