I have a very strange problem.  I am using Outlook 2007 with a POP account.  
I suddenly have been having the following problem the last three days:

When I open new messages and read them everything is fine.  If I close
Outlook and reopen it then the messages are gone.  The messages are NOT in
trash or deleted items.  I have checked and my .pst file size is only about
60MB.  I ran scanpst.exe on the file and it found some minor inconsistences,
but said a repair was not necessary.  I chose to do the repair in spite of
that.  However, the problem persists.  I don't have any rules set up so I've
ruled that out.

I'd appreciate ANY help that can be provided regarding this problem.  Thank
you.