First thing I would try is to unplug the usb connector, then reboot, then plug it back in & see if it gets recognised.
Otherwise the only other thing I can think of is to uninstall everything & re-install...
- not having XP or an external CDRW I don't really know what else to suggest, although using Win98se I have found that some devices will work via a usb hub, but not plugged in directly??? - that may be a complete 'red herring', but I believe it's to do with the hub somehow managing to handle the power requirements for the devices, better.
- hope you get it sorted, Incog