I notice, from time to time an old thread gets brought back to life, often with someone posting some short comment that does not really add much of anything. Often times the thread has already run it's course and it would probably be more worth-while to start a new conversation if you want to discuss it further. On occasion, old threads are updated by someone with new and useful information, so simply locking them may not be the best way to go.
I'm curious if the forum software would allow for a warning message when you attempt to reply to an old thread: "Are you sure you don't just want to start a new topic instead?"
Here is what the reply box looks like on another forum I occasionally use:
JGL
