UBB.threads PHP Forum Software Community Forums UBB.threads 7 Version 7 Support error trying to post new topics

I just tried to test out my newly installed forums and got this message when I tried to post a new topic using FireFox. I did't get this message with Explorer and was able to post successfully :

UBB Error
The host from which you are accessing the board is not recognized as a valid host. This is more than likely related to a firewall issue that is blocking the referer variable. Check your firewall settings and try again.

Please use your back button to return to the previous page.

I also turned the firewall on my computer off and got the same message.