If you tick "I'm not a robot" and then type your reply, the captcha expires before you have finished typing. But it appears at the top so seems like you should click it first. I am just in the habit of clicking it last now. I wish there was some, "I've posted here a while now and have not been taken over by robots in the last week, can I please not verify that I am a robot every time I post" kind of thing. At least if you just do one post. I could understand having the captcha kick in if you post 5 messages in 30 seconds or something. Anyways, just MHO. I've never been in the glorious position of forum mod though so maybe you get more bots that I realise.