I moved my catalogue (LR 3.3) form pc to a new Mac Pro, using the procedure set out in Victoria's blog. The catalogue appears to have moved just fine, but when I try to work with any image file, they all have the little question mark indicating that LR cannot locate the image file. I click on it & show LR where the image file is, locating it on the external hard drive where I keep all the files. It refuses to use that file, giving me an error message: "the file 'xyz.NEF' is already associated with another file in the catalogue'. Then to bring matters further into the twilight zone, it offers a button to click to 'show in library' (presumably show the "other" file it thinks is associated with that name), if I click it it takes me back to the original thumbnail which still has the question mark. How do I get LR to see the files?