When I goto UserCP to see my subscribed threads with posts since my last visit or click on new posts, it's only showing posts since 09:36 AM this morning. I haven't been on the site since about 6pm yesterday. What's broken?
I haven't made any changes to the site recently that would affect this. Your browser generally feeds cookie information to know what is new and what is not, so it's likely that the forum cookie expired or got deleted and/or you changed the way your browser handles the cookie.