I have been using the search feature to read through all my old Renderosity forum thread posts starting with the oldest (dated 4:02AM Wed, 07 July 1999). In those old messages, the text is always de-formatted, which I can cope with; but their attached images are also gone, leaving a "torn sheet of paper" icon instead, and the attached image was often the main reason for the message.

At a message posted at 8:59AM Wed, 16 March 2005 I at last ran into 3 messages which still have their attached images; but after then the images are gone again.

What caused loss of all those old images?