What behavior do you see? Does the board work on any other computers? If it does, but it doesn't show up as a serial device at all on that one, you might try emailing FTDI support to see if they have any ideas: support1@ftdichip.com
What behavior do you see? Does the board work on any other computers? If it does, but it doesn't show up as a serial device at all on that one, you might try emailing FTDI support to see if they have any ideas: support1@ftdichip.com