Every few days, when I restart Outlook, the search index is gone. So if I try to search for an email (from among my 1500 emails), it reports " results may be incomplete" . It takes between 15-30 minutes to rebuild each time. Is there some setting that needs to be set so that the index persists? (The general Windows search function works fine and doesn't need rebuilding). Running Windows 7 Pro 64 on an SSD.