mhhhh odd...
sounds like 5vsb as well...
is it possible to boost 5vsb by connecting it to 5v?
i mean the problems you guys have is with the board running, not in standby mode... so using 5v instead of 5vsb should work?
i remember that my 5vsb was too weak a few years ago for my dfi nf4 board and it had a jumper to switch to 5v instead of 5vsb, and voila, no more usb related problems...