Have you seen one of these? They are known as Word Verification or CAPTCHAs - you are to enter them when you comment on blogs in an attempt to prevent spam etc. This is Bloggers latest version. You have to try x number of times before you get one right. Who wants to make comments at such a blog? So what is the alternative?
- Remove the word verification on your blog completely (leads to more spam, but might be manageable)
- Have a totally moderated blog (not my style, at least - people want to see their comments at once)
- Stop blogging.
PS for discussion, see e.g here (there are many others):