OK, so I tried to something to fix this. I moved all my music to the hard drive on my computer. Placed them all the tunes in a folder and then deleted all the old music and imported again from the new folder via File> Import> Folder. Let Reckordbox do it's thing, while I went to bed. Hours later and everything was fine. Closed down Rekordbox, then re-opend to find that loads of BPM's and Keys had been lost again, and the it had duplicated loads of tracks. I wondered if it had duplicated them, but one of the tracks had the BPM and Key but the other didn't, but no, it's random as hell! Take a look at the screen dump, you'll see at the top for Example, Digitalism and also look down, Dirty South vs. Red Hot Chili Peppers.
Please help! I have saved up long and hard to buy CDJ-2000's and a DJM-2000, the first Pioneer DJ gear I have ever owned, and the first experience I'm having is a nightmare!