Nikon coolscan 4000ed forum

I have recently purchased a used 4000ed scanner. Had to download s/w from Nikon (ver. 4.0.2).
The scanner worked fine for about a week, then the s/w wouldnt recognize the firewire device.
Have tried reloading s/w without success. S/W comes up ok, but errors w/ "unable to find any active device".
Have contacted Nikon, but not much help so far. Anybody have any ideas?
Using AMD Athlon 64 x2 on MSI motherboard w/plenty of RAM and storage.
Windows XP Home OS. I suspect firewire drivers but cant find source within Nikon s/w.
Thanks for any support.
R. Daniels