I am running Windows 7, Outlook '07 and really don't recall changing anything recently? I went to the Indexing option and find all of my "In" folders are check marked, which I hope is what I would want?
And to the idea of searching for an email more recent than the date, I tried to search for one email received about an hour ago, by entering the senders first name (part of the email address) and nothing shows, just ones prior to the 10/15 date?