The other forum was on the same server as the Rhiannon3.net website, ie it was a subdomain of the site. For some reason the whole site has gone, and with it the message forum which was effectively part of the site. We have not been able to contact Kim for quite some time (which is why there was nobody with moderator rights on the forum), but she holds the rights for the domain name until October 2014. This means that theoretically at least, the site and forum should have been securely up and running until then at least. Sites usually disappear when the registration for the domain name has not been renewed, which is not the case here. Other possibilities are that the server (ie the physical machine on which the data was stored) has failed, or that the site is down while being transferred from one server to the other. I have checked out Kim's other sites and one has not changed in years and no response from the contact address, the other states that it is in the process of being upgraded, but I do not know how long that message has been there. The fact we have not been able to get hold of Kim Eyer for ages did mean that we had some warning that it might go down at some point, but since the website was not due to expire for another 10 months, I did not really think it a risk at the moment.
That was the long answer! The short answer is: it disappeared, we don't know why and no real warning. If Kim get's it back up again and contacts us, we can all go home