I tried to remove any code pertaining to that both in the header insert and in the body tag, but it did not resolve the problem.

A bit more info:

Looking trough the actual output on the page, Firefox and Opera simply embeds ../images/general/default/blank.gif where the CAPTCHA image should be output.

WebKit browsers, however, output
Code
ubbthreads.php?ubb=captcha&id=<sessionid>&t=
which, when clicked, produces
Code
ubbthreads.php?ubb=captcha&id=<sessionid>&t=gd

Edit: Or rather - that's the images' link.

Last edited by Kefas; 01/20/2011 1:42 PM. Reason: Update