That'll require a lot more than what you just told me.
What message does he get?
Can he post on any other phpBB forums?
Can he post through a proxy such as Guardster?
Has he tried different browsers (Firefox, maybe)?
He's tried a bunch of different browsers, cleared the cookies. etc etc... It might be some funky "internet protector 3000" software jamming up the works. He's tried everything else.
