help with Microsoft Outlook

I set up a new email account for the receptionist in our office two weeks ago, all was going well until last week. When she receives an email , as soon as she clicks on it to open it, it completely disappears from her inbox. None of the settings have changed since the account was set up, so Im at a loss as to what could be the problem. any one got any ideas to to remedy this?

click view, current view and click messages. 20 cents says shes got "view unread messages only" set.

thakns car, but that was one of the first things I liked at, its set to view all messages.

Check that filters have not been set up in the client. The emails must be going somewhere – it’s possible they are in Sent Items or Outbox and they may even be “hidden” in these folders. Look on the left hand side of the pane and see if it says “filter applied” when you highlight any of the folders. If you so you can remove any filters by going to View, Arrange By, Custom and ensure Filter is set to off.