@Ghost_chu and @KazeroG
Editing core files is not a good idea, as these can be replaced without further notice at any time. Therefore we should not recommend these measures.
MikeJones
Looking at your forum, I can't see your discussions as marked no-index. So I have no idea, why Google Webmaster should treat them as such. But I guess that the above mentioned recommendations wouldn't change anything.
Probably someone else has an idea.