Hi there, can anyone help? I bought Aperture 2 many months ago, but found it wouldn't work on my Powerbook G4. I then switched to Adobe Lightroom, and put the Aperture software in the cupboard. I've just sold the software, but the new user gets the error message, 'serial number invalid'. It's possible I entered the serial number (can't remember), but the software itself was never used. How do I get the software to work for someone else? Many thanks for any help.