I attempted to create a new user on ur system, but the captcha is sooooooooooooooooo hard to even see properly that its extremely hard for even us humans. Perhaps, could you tone it down a lil bit? or use another system? I would suggest you try entering the captcha ( the read numbers from the images to prove you are a human thingy ) yourself to see how difficult it is..
I had to get 3 people from my office to see what exactly was written in there.