Using the quote button to quote and reply to Kat's post on the October Club Night thread, I got a validation error message and it refused to post. I tried posting it several times, and just previewing it, all to the same effect. After I copied it into a reply without using the quote button it worked fine, however, and I cannot reproduce the validation error with an identical post.

Windows XP Home Edition with SP2 (no choice on this laptop), Mozilla Firefox 2.0.0.7