This is a Firewall issue, and most likely because of the Referrer Check features built into newer versions of UBB.
I'm not sure what version of UBB this website uses, but I have heard on other forums that in the UBB configuration, there is a Referrer Check feature. The basic purpose of this option is to check legitimacy of the poster, and to protect the board from spamming, etc... I'm not sure if the website moderator is watching, but it appears this problem started on versions of UBB 6.5 or later. In previous versions the referrer check is turned off. This can be disabled in the config utility by the moderator, but really is a security feature that was added. To disable go into Control Panel, go to Master Settings: Primary Settings. On the General tab, expand the Advanced Options (by clicking the + sign). Check the box after "Disable HTTP Referrer Check?" Then save the changes.
More than likely the moderator will not be willing to disable this feature. So the other alternative is for those that have firewalls running on their pc, to check the configuration, as they are all differant, and to allow the Referer Variable.
good luck
