[development] Automatic disabling of comments

I have seen this done on the web and surely there is a module in Drupal, but after half an hour of seraching can't find it. I need to set comments, preferably by content type, to disabled or read-only after a certain length of time. I don't think it would be hard to write, but I'd hate to re-invent a wheel if it already exists. Does anyone know of such a module?   Nancy   Injustice anywhere is a threat to justice everywhere. -- Dr. Martin L. King, Jr.