Sometimes I tried to post after the articles. However, after I filled the text box, I often got:
ERROR: Captcha time expired.
So how can I post my comment?
Maybe you just took a bit too long to write your comment? Not your fault of course. :)
Captchas tend to expire after a few minutes and need refreshing to prevent possibly malicious re-use.
I tried to post it in a short time, and it has been post successfully.