Hi Wang Baode,
I'm having the same problem that you had.
Did you solve this? I'm wondering if it is related with my account, because I'm not the computer admin.
The problem I cannot log as admin, I will have to wait next week and ask who can if I do not solve today.
Thanks.
Frederico Luiz
Dear Frederico Marcelino,
you can try other USB interface of your computer. or try other cable.or Power off your computer for several minutes and retry it.
Dear Wang Baode,
changing the USB port solved the problem. Many thanks.