[Skyrider]

I took the liberty to check out your forum in person to see potential issues.

The avatar/images that isn't working in the thread view (when checking all the threads) isn't working because the link is all screwy.. for example:

https://www.yoursite.com///www.yoursite.com/customavatars/avatar27383_3.gif

(replaced your site with a template site).

unknown.gif avatars are working fine, as I assume you have some kind / type of default avatar for people of whom has no avatar set.

Now, within threads I noticed that the avatar links are somewhat correct, for example:

https://www.yoursite.com/customavatars/avatar41635_4.gif

However, it links to your main website when I attempt to directly view the image. Seeing that happens to everything that the site doesn't know, (404) I assume you set it like that to move them to the main site instead.

So, my thoughts:

1), File / web path of the images and or avatars might be incorrect. (double check this in the admincp)
2), Forum path might not be fully 100%, try to set a direct home path through the config.php or double check the admincp.
3), your https (of which works on the main page, but not fully working on the forums) might be screwing things up.
4), Some kind of addon might causing problems.
5), Avatars are not being properly uploaded, see kh99 post above.

^ These 5 are my guesses that I would be looking into.

Are the avatars saved as file or within database?