UBB.threads PHP Forum Software Community Forums UBB.threads 6 Version 6 Support Error Posting

"the host you are trying to send input from is not a valid host

I have a group of people in the same office that is not able to post to our forum.
They are able to login and read just find. but when they try to post they get the above error.
They are all using windows XP with the lateses IE explorer

I am not sure whats going on. I have a lot of other users that are able to post just find.


I am running 6.5 but tested it with 6.5.1.1 and the still get the same error.

I am running php 5.02 and MySQL 4.1 on Windows 2000 Server.

any clues?? <img src="https://www.ubbcentral.com/boards/images/graemlins/confused.gif" alt="" />