firewire device problem

Ihave 2 external hard drives with usb and firewire connections.. they work fine on usb but not firewire… also my panasonic camcorder is not now recognised on firewire connection… it comes up as ‘unknown device’ in device manager
the 1394 controller is shown as working correctly in device manager .. is there any way i can test to isolate the problem .. beginning to think all 3 devices are fried.. running xp home by the way