John, Thanks for that. I have had success by uninstalling Lr3, spending some tome on my Lr2 using 'cmd' 's' to save all my rated images information to XMP and optimising again Lr2. I then reinstalled Lr3 but this time on an external HD and File >imported the Lr2 catalogue. All seems well so far, so I'm not quite sure which procedure helped but happy to be up & running. Thanks for your help. Andy