Visual verification code - It doesn't work. What should I do

Sometimes it happens that the visual verification code (aka CAPTCHA) doesn't show up in the registration page.

The two most common causes of this problem are:
 * 1) one of the php files involved in the creation of the image doesn't end with  or doesn't start with
 * 2) the fonts directory is missing or some files in the directory are missing

It's possible to quickly scan all the files of the forum in order to look for leading or trailing empty spaces or lines by using file_check.php. For each file reported by the script you have to open it and remove any leading or trailing white space or new lines present and in general any character from the beginning of the file to  and from   up to the end of the file.

The fonts directory can be found in the default's theme directory. It can be replaced by the one from the install package in order to restore any possible missing file.