I've seen it happening before, and it's happening again for me now: I can't reply to certain forum posts even though they have a reply button. My reply just gets eaten and doesn't post; the page reloads and everything I've typed is gone, the page looks as if I've just opened that forum thread.
An example is the latest posting on the thread about international entries in contests: I can't reply to the user from Taiwan who is asking whether s/he can enter.
There is no error message or anything. This is frustrating and makes me not want to use the forums anymore.

If it helps: I'm using SeaMonkey on XP.

Can anyone enlighten me?

Edited to add: it looks like I can't even post a new message (this one). I keep ending up on a blank page. I gave it several tries but it didn't work... then, ten minutes later, it worked.