i realised today, the captcha is just not working...
not in register user, not in contact form...
there is an empty place for captcha image, but the omage do not loads
Best you look for your CGI logs and see if there are any errors. Also check on the admin tabs and see if the captcha image shows where you can select the font.
You will have to ask your service provider for help with the CGI log. That is the place where the server records errors that scripts encounter. I am sure this log will be necessary to figure out what is happening.