When I disabled it I got a message saying "disabling this device will cause it to stop functioning" I press ok, then it refreshes and is no longer on the list. It was in (PCI) 0x00000010 (17)
I no longer get this category listed only 16 and 19.
It could be just hidden, under view(or right click) there should be a "show hidden devices"
Or turn off, remove the firewire, reboot, turn off, add it back, go to the device manager and "scan for hardware changes"
Or might have to do a system restore if you have a recent one.