Usb/firewire ext. disk

Hello.
I have a serious problem with my rxt. usb/firewire disk.
I have an 1394(firewire) card installed (windows forces this card to use
OCHI driver and i want it to use Texas Instrument driver) that is impossible
becasuse windows says that the driver has the best driver. This result in a
freese/no detection+++ after a windowsupdate patch. (after a clean install
with xp sp1 everything works).

If i give up firewire connection and try to use USB connector it will not
detect my ext. disk. ( this also worked before sp2).
The only way to use it is to power it on after windows is started, then it
works. That is not good enough because i want to share some files on that
disk.

I tryed to install (WindowsXP-KB904412-v2-x86-NOR.exe) driver but that
resulted in 30 min of rescuingwork because the maschin tilted and did not
start propperly afterwards.

Config.
Dell 8400 pc with 1gb memory and prosessor 3ghz.
the usb disk is tested alone so there is enough power to use the disk.
the usb connector is functional.
the usb disk has external power.

Rune