I open an email in my inbox and when I close it it disappears?

[F.H. Muffman]

Just as an FYI, it is really really super helpful if you, y'know, actually
put some text in the message to explain your environment, the situation,
and, again, the environment like what version of the product, if you've done
anything to try to fix this, how long the problem has been happening, any
changes you might have made, etc etc etc. Saves us from having a whole
bunch of back and forth with you while we try to puzzle out what could be
wrong.

That said, it sounds like you have a filter on to show only unread messages.
What does it say down on the status bar?

 

[Joe Grover]

It sounds like you have your view set to show only unread messages--once
you've read it it's marked as such, and doesn't show up anymore.

In Outlook 2003, you'd click on View -> Arrange By -> Current View and click
on Messages (my guess is it's set to Unread Messages)

Joe