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Windoze = windows, 60125 bugs included
Have you tried the other usb-ports?
Since the error happens many times with the same files, can you put all the files in one folder on another partition, so completely unfragmented, to see if the error is there? Or burn them to a disc, transfer them to the device, and see if the problem is still there.
Are there other usb-ports in use, is it possible to disconnect the other devices from them, at least switch 'm round, might be the combination device/port.
Them nforce4 chips are troublesome with maxtor drives relating file transfer, that's why I mentioned it, you might have a maxtor, or not.
Check device manager for other devices using the same irq, submenu "view-resources by connection", if other devices share the same irq, let us know.
I/O errors usually are memory management problems in windows, that is, different devices using confilcting segments of the memory.
Sometimes it can be changed,
through device manager-hardware-rightclick the usb controller-properties-recources-
if it is possible there for you to give the usb-controller a higher memory range, it might work. Even better if you can give it another irq.
I've heard of the problem on the internet occuring after an update to winxp service pack2.