USB/1394 case problem

External USB/1394 case works fine with the USB plug attached, but wants to format the disc when hooked up to firewire port. Looked for drivers, but says none are needed for Win XP Pro. Case is silver with two plastic rails that snap in place to lock the top and bottom halves together, but no brand markings (a number of years old) has an Oxford 911 chipset, and looks very similar to the Potecc ME-320U2F case. Any help would be appreciated.