plugging in firewire shuts down the machine
I have completely lost all fire wire on both my Mac Book core duo running OS 10.4.11 and my Mac Mini. When I plug a cable into the Macbook, the machine shuts down. the Mac Mini just doesn't see any fire wire connected equipment. I cannot use my Panasonic or Sony digital cams or connect my OWC Mercury external drive (it will connect thru USB)
On both of your macs open up system profiler and click more info. In the side bar look for firewire and if you see it click on it. If the problem is with the port itself then it will say " Firewire: No hardware was found"(or something of that sort). This means it is a issue with the port. It may also be an issue with the cable that you are using. Try a different cable or try running the apple hardware test with the install disks that came with your computer. (also is it any device that you plug into the macbook that makes it shut down). Tell me the results of what happens so I may help you further.
Hope this helps.