Tough reading everything but, have you guys tried Disabling the Onboard Audio in your BIOS?
Since this is an External USB device, perhaps there is a conflict with IRQs once you start the game? conflicts with USB mouse or Keyboard I mean. Just for testing purposes, have you tried disabling the USB ports not in use when playing?
I would go to Device Manager and check which IRQ is being used by the Mouse, KB and External Audio device, if same, try changing it manually or uninstall and let windows choose another IRQ.
Sorry, perhaps not much help at all but I have never seen this problem before.
I think that someone mentioned testing playing the game with Onboard sound instead of external device... was this tested as well?