As several other people have complained, I also have a numnber of unasked for duplicate Personal Folders, and also had a problem when the one I had all my data in disappeared. Eventually after restoring an earlier safe point I got it back, only for it to disappear again when I closed/reopened Outlook.
After some research I gave up, re-entered all my current data and renamed the Personal folder I had used as PersonalFolderActive. Everything was fine until today, when that folder disappeared along with all my layest entries. It was there when I switched on, there when I entered data in my calender, and there when I went to lunch, with the computer switched on. When I came back, IT HAD GONE! So had all my recent emails, my sent emails and my latest calender entries. My contacts list is now back to the old entries, all my updated ones have disappeared. Help, anyone!
Nice idea, but the real problem is that the actual Personal Folder I was using has just gone - any search only shows the duplicates which while they work have outdated data files and so I am still missing all my most recent information.