Its definitely an internet routing problem then and not something with your personal equipment. It may be due to your ISP or the internet routing in general.
You should drop the forum admins a PM with the above details so that their server guys can assess the situation and see about getting their DNS servers altered.
Also it may be possible for you to re-route your connection to them by using a different DNS service other than your ISP. Give
OpenDNS | Providing A Safer And Faster Internet a try, its free and far more reliable than your ISP is ever likely to be. Its what I use all the time.
Hope that helps
