Yeah, that message is from one of the spam blockers I installed. I believe that one is supposed to check the time it takes to fill out the form and when it's submitted. If the time is below a certain threshhold, it displays the error message. But it also seems to do it if a you leave the posting page up for a long time.
I'm working on fixing it. For now, a workaround is to go back to the posting page and copy the text of your post refresh the page, paste your text and submit.
If you're stupid, surround yourself with smart people. If you're smart, surround yourself with smart people who disagree with you.