I do not know the cure, but here's a workaround that seem to work for me.
I am using the Firefox browser on a Windows 7 PC.
Whenever you see the dreaded red-x where a real picture should be, hit the "reply" button at the bottom right of that specific message. That will open a reply box at the bottom of that thread page and that reply box will include the pictures embedded properly. You can scroll thru it to see the entire post.
When you're done looking at the pictures (and if you don't really want to reply to the message) you can get rid of everything in that reply window by simple typing <ctrl><a> and then hitting <delete>.
Note by <ctrl><a> I mean to press and hold the key marked "Ctrl" or "Control", and simultaneously press the key marked "a".
This is a windows shortcut for "select-all". Then the "delete" key applies to everything that's selected.
-brino