Trust me its not on the hosts or the registrars side. I have talked to them numerous times, and both the registrar and host says its guaranteed an isp problem.
the only way of it being on the forums side at all would be getting ip banned somehow. Send me the ips via pm that you are not being bale to access fk with, and I will check if they are banned but I am sure they are not.
Isp's have a cache of their own. Which isn't cleared often. forumkorner.org has been redirected to fk for years. It's easily a cache problem.