Firewire external drive no longer detected

Hi There, I've been having some protracted problems with an external hard drive which i bought recently. Hopefully somebody can help.

The story:
I have a Dell latitude C840 laptop running Win2000 SP4.
I bought an IOGEAR ION 40GB Firewire/USB2 external hardrive for making backups.
I use the firewire connection as the laptop only has USB1.1

The drive worked almost flawlessley for a week and then sometimes it would intermittently not detect on bootup or after plugging it in, but usually after switching it on/off a few times it would detect. This was the case for a few days, but then no matter what I did it would not detect at all.

What I've tried:
1. Uninstall/re-install the TI OHCI compliant IEEE1394 Host Controller - No difference
2. Replaced the Firewire cable - No difference
3. Tried the drive with other PCs (2) - The drive works fine with other PCs
4. Tried the drive with USB1.1 ports - it works fine but is painfully slow.
5. Formatted HDD in the laptop and reinstalled Win2k + SP4 (I thought it may be a corrupted registry or something) - The drive worked fine again for a few days, but then the same problem reoccured - The drive worked intermittently, then not at all.

I'm at my wits end with it. I've tried the Dell and Microsoft support sites, but no joy.
The closest thing I've seen on Microsoft site is Q329256 - which seems to have worked for other people, but this only applies to XP not 2000.

Does anybody have any suggestions?

Thanks,

Paul.