Ever since it was added about 5 months ago? I detested this feature - that you have to solve a captcha before you are allowed to post a new post. Sure that wouldn't be a problem but the first captcha image that appears ALWAYS gets identified as incorrect although I type it in correctly. Is there a way to turn this off? I've noticed it's only active on older blogs as I created another one last week and it's not on there.
You should be able to update your older blog to the new templates, etc. and get rid of this feature. Try going to Template>Edit HTML See if it gives you the option to upgrade to the new template, etc. there. It shouldn't change your template, it should just pull you out of that classic mode that requires the captcha. I can't test it on my blog for fear of screwing it up.