Threads locking themselves?

I have no idea whats going on in my forums, but whenever anyone posts a thread it gets automatically locked.

The only people that can reply are admins and moderators. I really have no clue as to which hack is causeing this because the froums were working fine. If anyone has ANY ideas at all help me out please.

[Gary King]

Try replacing your current copy of newreply.php with an original.

[rz-lithium]

We've already tried that :/

[tmapm]

A list of your recent hacks up to a time you KNOW it was working for sure might help..