It's not a windows XP usb problem, but a problem with the DFI lanparty board's usb.
An official DFI technician emailed me this answer -
Sir I have referred similar incident to engineering of DFI in Taiwan and they are working to determine what resolution is required. No concrete word at this time. Thank you for contacting tech support.
I have the same problem on my DFI LANparty NF4 SLI-DR.
If i have a usb device in at startup it freezes at the post screen.
If i try fitting any in windows i get "device cannot be recognized error"
Any help is greatly appreciated.
Andy