OK, thanks.
I tried plugging the board into a Lenovo Thinkpad Edge running 64-bit Windows 7 Enterprise, Service Pack 1 on a 2.3 GHz Intel Core.
It replicated the earliest behavior I saw on my own machine: Windows did recognize the device and try to install drivers for it, but failed after about 2 seconds and then immediately tried again, in an endless loop. Nothing appeared in Device Manager, under Ports, Other, or Unknown Device, and the Device Manager was also endlessly refreshing every ~2 seconds.
I tried putting my unpowered Targus USB 2.0 hub in the middle, and this behavior did not change at all.