firewire devices not installing correctly

I've got a cdrw and a dvdr in a couple of external
firewire boxes.

Windows xp keeps detecting them as removable disks rather
than cd burners and dvd drives, respectively.

Before this I had a plextor drive in the same external
enclosure and it detected fine.

I read something about xp misdetecting drives in this way
before sp1, but I have sp1 installed and it's still doing
it.

This results in all my burner software thinking I have no
cdrw's installed to use.

How do I remedy this?

R Lawrence