I think that what causes some images such as the avatars to sometimes drop out is the various url's being used. With individual sites changing settings or going offline, some of us using filters, etc. the images become unavailable.
I don't agree with that because it only happens when I can't see smiley's (emotion pics). There are times when the URL thing is true, but that is a different thing all together. When the forum is messing up the avatar is just a box with a red x in it. When a URL is messed up the picture just disappears.
LOTW, this most recent incident only affected those of us that block referers.
How do you know that? And what are referers? And why does the problem crop up and go away on its own?
I'm just saying that there can be multiple causes and differing effects for each of us.
As an example, if I were to filter out www.lunarsoft.net or lunarsoft was temporarily unavailable, I would not be able to see your avatar but I would be able to see all the other avatars on this thread. This could explain the "some will show and others don't" situation you mentioned.
In this recent incident, like LOTW, I lost all the images on the forum and got the red X placeholders. I tested a hunch and found that unblocking Referers corrected the problem. I contacted MrG and he confirmed that he had temporarily changed settings for a few days. Those settings would only have affected those of us that block Referers (see article). At other times, other setting changes may have been the cause, and may or may not have affected all of us.