Thanks for sending your site information. Wanted to send you an update, though I don't have great news to report just yet.
We got into the site, and we can see the JFBConnect image being imported (it goes into the /images directory as jfbc_12345_tmp.jpg). However, it's being written as 0 bytes. We've never seen this issue, and are not sure what's causing it. It's not related to Kunena at all, it seems to be a problem with writing that file to your server. We'll try to run some more tests on our site to recreate it, if you know of any reasons that it might be failing, please let us know.
The only strange thing we saw on your site was that if we go to Help->Site Info and then click on PHP Information, it comes up blank. We've never seen that, and it makes it more difficult to know your full PHP configuration. Again, if you know why this might be, or know anything about your specific server configuration we should know, please let us know.
Alex