I had problems with my LaCie external firewire CD burner no too long ago ( on 10.3.x... have had no problems so far on 10.4) where it wouldn't recognize the blank disc -- I discovered an esy fix was to hit the power button to turn it off and then on again.
I'm not sure that this fix will work for your situation, and if not I suggest removing the plugins and seeing if it recognizes the drive then (you can also check to see if updated versions of the plugins are available that may fix the problem). Try re-installing the plugins to see if you get functionality back. If not, you may need to remove the plugins completely and download the combo installer of 10.3.9 and install that. If nothing works, all that I can suggest is a reinstall of 10.3.