Okay, now I know something is screwy on my end.
I mean, I posted to a thread, got shown the post and then flipped on to the forum main page, only to see it wasn't there.
I check the thread again, and sure enough its not there.
Naww I say to myself, and go back to the main page and hit refresh again and again until it switches.
Took 5 tries but there it was. Hooray.
So yeah, I think it might be a caching problem on my end mixed with a silly firewall. I'll live with it.
Just FYI should something else similar occur.