I'm probably making assumptions, but I believe most newbies to this forum misunderstand the forum we once knew as "Other" with the General Discussion forum of SSF2. I believe new users receive a PM upon entering that encourages them to introduce themselves to the community in this topic:
viewtopic.php?f=30&t=42017
This has definitely worked for users to introduce themselves, but seeing how this is the first section most newbies visit, they probably mistake it for the main SSF2 section, misbelieving the entire forum is dedicated to that game, so most newbies post something SSF2 related when the section isn't dedicated to that game.
Also, the FAQ in that forum isn't clear on stating it isn't the SSF2 section:
viewtopic.php?f=30&t=40754

So, there are 3 possible solutions to this:
1- Rename the section to something that doesn't sound so vague which could be mislead as being part of SSF2.
2- Edit the FAQ, specifically saying it isn't the SSF2 section.
3- Add a link to the SSF2 section in the welcome Private Message.

We actually haven't implemented the automated private message yet, but I believe when we do it'll deter people from posting in that section mistakenly because we'll have something specifically stating not to.