You know, the only time I ever got something similar was when I was at my job using my notebook. And that was obviously because the network was messing up something.

Are you on wireless?

Yep, you're right. If It would be for me only I would probably still be on Arachne.
But you see, sometimes there are some bloody #@#@#@# critters crawling around here, and they want to be able to download/save easily their fav (youtube etcetera) clips, so yeah ..... *sigh*

****> example

I am not on wireless.

For example, right now I can read the second page of this thread, but if I go to the first, I don't see my own post. If I open it on another browser, like IE I can read all posts, including mine. I can't help but feel something is wrong with the forum caches (i.e. I am looking at an old cached page), but no idea why.

Mayhaps this topic about cache problems with FF can be helpfull ?

I downgraded back to 3.x, let's see if it helps.

Edit: Seems to be working well so far. Shame on me for blindly upgrading, I guess.

As a side note, I noticed they jumped from 3.x to 14.x in less than an year. I think it was a poor choice of version numbers, since it hasn't changed much. Also, 12.0 was using memory like hell, forcing me to constantly restart the process, to avoid hogging the machine. So far, 3.x seems to be managing the memory way better. So, I don't think it's wise to upgrade Firefox for now.

I've just (accidentally) upgraded to 12.0 myself.
I've changed some of the meta headers used to prevent caching.
It's possible that one of the headers added during our previous attempts to resolve this very problem may have been aggravating it instead.

A little testing later I think I have the right solution. You'll need to remove any currently cached pages from the forum (or empty your cache) in order to ensure it takes full effect.
Let me know if you still experience the issue.