Fixed the problem. Had to manually add my new project bin path to ~/ Library/Preferences/Macromedia/Flash Player/#Security/ FlashPlayerTrust/flexbuilder.cfg. This should have happened automatically but I suspect Flex builder 2.01 (on Mac at least) is a little flaky when it comes to moving projects around. Certainly seemed a bit broken for me, but maybe I was just using it wrong.
Guy
