I just went through the motions of ignoring the altcoin discussion board and then using the link in this thread to access that post and try to quote it; I am hit with the exact same error message.
On trying to create a reply, the message box opens, but I didn't try to send a post to know if I don't get an error message back as well.
Thanks everyone for your responses and checking the error. It resolves the issue. New learning though. I will lock the topic.