automatic lock every topic?

Would it be possible to automatically lock every topic that has not been posted in for over 6 months?

The reason is that people keep dragging a lot of older topics that nobody cares about any more back from the dead. And I'm sick of it.

phpBB boards have the option to "prune" topics if there is no activity in them after the specified time period in the admin board panel.

However this would delete them entirely from the database (and I doubt that would be desireable). I can't recall that there has been a mod written yet for what you are suggesting . Test your skills -- you could write it! But wait -- don't! sometimes year old problems people find on Google, may be worth bringing up again.