You are going to the right place with your link. It is a web-site that thinks it's a forum

that we can customize to make it behave the way we want it to. Eventually, after Ifan has used his spinners on it. Have to say he's rather a deft spanner-user, imo.
Sub-forums will be replaced with a different idea - tags. Once those are in in place they will be easier to use.
The organisation is pretty neat, isn't it. That could never have happened in the same way on a PHPbb forum, nor was it designed to be. Again, that's a combination of Aran's vision and Ifan's work, although he was off to a start because the original coding work was started by Jo.
The posting error is result of this forum being upgraded and SSiW not going with that expense so close to the launch of the new, bespoke site. As you have found, the error doesn't prevent posting...
Firefox is good, but IE problems do depend on how good your Windows installation is, and which AV package you happen to be using. Firefox freeze
may be caused by a dodgy video card, either the driver or a hardware issue.