If you have any problems with replying to threads. Please read on(of course if you aren't having any trouble you can read on as well, but there are more interesting threads than this one:P: )
As far as I know everything works fine when you use Firefox.
But I noticed a problem when using Internet Explorer. When using internet explorer 10 I'm not able to reply. I don't know if this is also a problem with an older version.
Google Chrome works fine as well.
Safari also works good.
So, when you're using Internet explorer, try using another browser.
PS. Dear Mellon, sorry that it took so long. I sent you a message about the fact it could be your browser, but I'm not sure if you received it. Anyway, I hope it works for you again if you use another browser.