New
#11
Thanks for your thoughts. I've installed from scratch W7U x64 and x86 on this system in different partitions--they are fine. The USB problems are related to UR.
MB comes with 2 'internal' USB 3.0 ports (in faceplate) and 2 'external' USB 3.0 ports (uses an adapter slot-location but not an adapter slot). I unplugged the 'external' ports, still no boot.
As it happens I also have TIH 11 with UR. I'm going to try that assuming it can deal with a backup created by B&R and/or the B&R OS image as restored by B&R. Does anybody know? But I guess I'll find out in any case.