I've got a weird issue for one of my users.
It seems whenever he types a name in to the "To.." field of a new email, the search results shows the same repeated name for the list of suggested contacts, and then when you go to click on that name it populates with that person instead of the email of the person you typed in.
At first I thought it might have been a corrupt Outlook profile, so I deleted the pst file, rebuilt the Outlook profile etc., but it was still happening. Then I noticed that when he logs in to webmail, the same issue occurs. It's almost like he's got a corrupt address book on his exchange mailbox or something.
Here's some images so you can see what I mean: