Driving Mega2560 from external 5V bricks USB port

Note that I've sent emails to both sales and team at arduino.cc asking them to look at this problem AND to fix the broken zip file containing the rev3 reference design. First I emailed sales, then a week later forwared to team, after 10 days or so I still haven't received a reply and the broken zip file is still un-openable....nobody's home....