Oh... Sorry to have uncovered an issue. :( I actually don't have anything from photobucket on this particular account, but I still get the yellow exclamation mark, which does go when I use an extension to block images. So it mustn't only be photobucket images. (Just to be sure about that I just right-clicked and viewed the "page source" on firefox for my entries page on this journal, and did a "find" search for photobucket, but there was no result).

EDIT - no phobucket but it appears the lock icon for my entries and and the userhead on my custom layout are from imgur - imgur have http:// only links.