I have problem with the usb port on the right side. When I plug a usb hub into that port,then plug 2 usb into that hub to connect with my macbook, both usb disconnect and reconnect randomly, this doesn't happen when I plug usb hub into usb port on the left side. If I only plug 1 usb,the right one will work normally. I tried reset SMC,PRAM and install new Os but nothing changes. So is this an error or the design of MBP?