Losing emails in Outlook 2007

We have Outlook 2007 email. My mother thinks she did something when she was fooling around with it. Now every time we get an email, and then read it, and then leave Outlook and return, the email is gone. Not in the inbox (where it should normally be) and not in the other Outlook folders. Nowhere. Again and again. I have used the search function and tried to find the emails but they are gone totally from the computer--not in any folders in or out of outlook. They immediately become deleted permanently. Any idea what she could have done to cause this?

ps--she only loses emails that have been read--if they are unread, we can go in and out of Outlook and they are still there. HELP!

If you read an email it should still remain in the inbox. It will be removed from the unread email folder. Is it possible your mother is confusing the unread email folder with the inbox?

No, I am visiting her this weekend and am relatively computer sophisticated. Where they go I don't know but I do a search and they are not found anywhere on the computer. I tried a few test emails with unique keywords and search for them and no go. But I can find emails that are already in a saved folder easily enough. So they seem to be deleted (and not in recycle bin). I have Windows Mail on my computer so have no history with Outlook 2007--but I'm at a loss.