I see your having issues with communications with your legacy 16:4:2 over firewire 400 protocol. What you haven't done, or if you did I missed it, is verify that your firewire card is compatible. If it's an OLD computer with onboard firewire you would need to verify the chipset, that is listed in the above answer you posted. The location of the information is there as well. If by chance you do have the correct card/chipset, it MAY be bad...The cable could also be faulty, I have personally seen both. Perhaps a Tech service ticket is the best way to solve this if you don't have any other options, but try a different cable, a shorter cable if possible, or different firewire port/device. Until were sure these questions are answered moving on will be difficult. If this worked in the past these are especially pertinent questions. Also a wipe and reload of the software might help.