Okay, first up, I just want to make a comment about signing up for this website.
Your security precautions are quite simply over the top. Having to type in a security code from a captcha image 3 times just to sign up and sign in for the first time is ludicrous. And now I can see I have to enter another one just to make this post.
But the real problem is that it is quite difficult to read the captcha. The whole idea of using an image to stop bots from spamming a forum is that the bot cannot read images. Some very clever ones can work out basic images, but beyond that, you'd be looking at a very desperate individual to use a bot to spam these forums.
I can only say, please be more realistic and tone down your security precautions. If you feel the need to use captchas for every activity on the site, then at least make them readable.