Today I decided to unlock all the topics that were auto-locked. I have this "mod" in my forum that auto-locks topics that haven't been written to in x number of days. A few times people have wanted to comment on older stuff but couldn't because the system had already locked the topic.
If this works out okay I'll keep the older stuff unlocked.
To note: "Locked" doesn't mean "hidden". It just means those older posts can now be replied to once again.