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http://www.theregister.co.uk/2009/10/30/iphone_p55_problems/
Looks like its a chipset issue, not sure if its the Apple driver or what, I have a X58 chipset as well, but both chipsets use the ICH10R USB hardware.
I went out and bought a cheap inland PCI adapter that uses a NEC USB chipset and tossed it into my machine and now I can sync, unplug, sync again etc.
Theyre about 7-30 dollars depending if you spring for PCI or PCI Express.