Problem with Outlook Express 6.0 registering emails for reading

We are having problem with my wife's email (Outlook Express 6.0) on her computer which uses XP Home OS SP3. First thing that happened was that her mail settings disappeared. I reentered them this morning, and then emails started coming in clear back to November 2009 (probably as far back as those on the server). Anyway, the only emails that visibly appear on her screen are those through 7/13. The incoming numbers keep advancing in the Inbox, but I can't find out where they are actually going, unless they are self-deleting. There is no increase in the deleted items folder number though. Any idea what might be going on here?